| 1. |
- Ahmadova, Nigar, et al.
(author)
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Formation of tyrosine radicals in photosystem II under far-red illumination
- 2018
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 136:1, s. 93-106
-
Journal article (peer-reviewed)abstract
- Photosystem II (PS II) contains two redox-active tyrosine residues on the donor side at symmetrical positions to the primary donor, P680. TyrZ, part of the water-oxidizing complex, is a preferential fast electron donor while TyrD is a slow auxiliary donor to P680 +. We used PS II membranes from spinach which were depleted of the water oxidation complex (Mn-depleted PS II) to study electron donation from both tyrosines by time-resolved EPR spectroscopy under visible and far-red continuous light and laser flash illumination. Our results show that under both illumination regimes, oxidation of TyrD occurs via equilibrium with TyrZ • at pH 4.7 and 6.3. At pH 8.5 direct TyrD oxidation by P680 + occurs in the majority of the PS II centers. Under continuous far-red light illumination these reactions were less effective but still possible. Different photochemical steps were considered to explain the far-red light-induced electron donation from tyrosines and localization of the primary electron hole (P680 +) on the ChlD1 in Mn-depleted PS II after the far-red light-induced charge separation at room temperature is suggested.
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| 2. |
- Allakhverdiev, Suleyman I., et al.
(author)
-
Vyacheslav (Slava) Klimov (1945-2017) : A scientist par excellence, a great human being, a friend, and a Renaissance man
- 2018
-
In: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 136:1, s. 1-16
-
Journal article (other academic/artistic)abstract
- Vyacheslav Vasilevich (V.V.) Klimov (or Slava, as most of us called him) was born on January 12, 1945 and passed away on May 9, 2017. He began his scientific career at the Bach Institute of Biochemistry of the USSR Academy of Sciences (Akademy Nauk (AN) SSSR), Moscow, Russia, and then, he was associated with the Institute of Photosynthesis, Pushchino, Moscow Region, for about 50 years. He worked in the field of biochemistry and biophysics of photosynthesis. He is known for his studies on the molecular organization of photosystem II (PSII). He was an eminent scientist in the field of photobiology, a well-respected professor, and, above all, an outstanding researcher. Further, he was one of the founding members of the Institute of Photosynthesis in Pushchino, Russia. To most, Slava Klimov was a great human being. He was one of the pioneers of research on the understanding of the mechanism of light energy conversion and of water oxidation in photosynthesis. Slava had many collaborations all over the world, and he is (and will be) very much missed by the scientific community and friends in Russia as well as around the World. We present here a brief biography and some comments on his research in photosynthesis. We remember him as a friendly and enthusiastic person who had an unflagging curiosity and energy to conduct outstanding research in many aspects of photosynthesis, especially that related to PSII.
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| 3. |
- Beckmann, Katrin, et al.
(author)
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On-line mass spectrometry : membrane inlet sampling
- 2009
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In: Photosynthesis Research. - : Springer Netherlands. - 0166-8595 .- 1573-5079. ; 102:2-3, s. 511-522
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Journal article (peer-reviewed)abstract
- Significant insights into plant photosynthesis and respiration have been achieved using membrane inlet mass spectrometry (MIMS) for the analysis of stable isotope distribution of gases. The MIMS approach is based on using a gas permeable membrane to enable the entry of gas molecules into the mass spectrometer source. This is a simple yet durable approach for the analysis of volatile gases, particularly atmospheric gases. The MIMS technique strongly lends itself to the study of reaction flux where isotopic labeling is employed to differentiate two competing processes; i.e., O2 evolution versus O2 uptake reactions from PSII or terminal oxidase/rubisco reactions. Such investigations have been used for in vitro studies of whole leaves and isolated cells. The MIMS approach is also able to follow rates of isotopic exchange, which is useful for obtaining chemical exchange rates. These types of measurements have been employed for oxygen ligand exchange in PSII and to discern reaction rates of the carbonic anhydrase reactions. Recent developments have also engaged MIMS for online isotopic fractionation and for the study of reactions in inorganic systems that are capable of water splitting or H2 generation. The simplicity of the sampling approach coupled to the high sensitivity of modern instrumentation is a reason for the growing applicability of this technique for a range of problems in plant photosynthesis and respiration. This review offers some insights into the sampling approaches and the experiments that have been conducted with MIMS.
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| 4. |
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| 5. |
- Björn, Lars Olof, et al.
(author)
-
A tribute to Per Halldal (1922-1986), a Norwegian photobiologist in Sweden.
- 2007
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 92:1, s. 7-11
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Journal article (peer-reviewed)abstract
- We present here a tribute to Per Halldal (February 2, 1922-March 26, 1986), a leader, an instrumentalist, an expert on phototaxis in algae, and one whom we remember, even after 20 years of his death, as a person who spread joy, enthusiasm and knowledge wherever he went.
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| 6. |
- Björn, Lars Olof, et al.
(author)
-
A viewpoint: Why chlorophyll a?
- 2009
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 99:2, s. 85-98
-
Research review (peer-reviewed)abstract
- Chlorophyll a (Chl a) serves a dual role in oxygenic photosynthesis: in light harvesting as well as in converting energy of absorbed photons to chemical energy. No other Chl is as omnipresent in oxygenic photosynthesis as is Chl a, and this is particularly true if we include Chl a2, (=[8-vinyl]-Chl a), which occurs in Prochlorococcus, as a type of Chl a. One exception to this near universal pattern is Chl d, which is found in some cyanobacteria that live in filtered light that is enriched in wavelengths [700 nm. They trap the long wavelength electronic excitation, and convert it into chemical energy. In this Viewpoint, we have traced the possible reasons for the near ubiquity of Chl a for its use in the primary photochemistry of Photosystem II (PS II) that leads to water oxidation and of Photosystem I (PS I) that leads to ferredoxin reduction. Chl a appears to be unique and irreplaceable, particularly if global scale oxygenic photosynthesis is considered. Its uniqueness is determined by its physicochemical properties, but there is more. Other contributing factors include specially tailored protein environments, and functional compatibility with neighboring electron transporting cofactors. Thus, the same molecule, Chl a in vivo, is capable of generating a radical cation at ?1 V or higher (in PS II), a radical anion at -1 V or lower (in PS I), or of being completely redox silent (in antenna holochromes).
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| 7. |
- Björn, Lars Olof, et al.
(author)
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Teaching about photosynthesis with simple equipment: analysis of light-induced changes in fluorescence and reflectance of plant leaves
- 2013
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 116:2-3, s. 349-353
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Journal article (peer-reviewed)abstract
- Solar energy absorbed by plants results in either reflection or absorption. The latter results in photosynthesis, fluorescence, or heat. Measurements of fluorescence changes have been used for monitoring processes associated with photosynthesis. A simple method to follow changes in leaf fluorescence and leaf reflectance associated with nonphotochemical quenching and light acclimation of leaves is described. The main equipment needed consists of a green-light emitting laser pointer, a digital camera, and a personal computer equipped with the camera acquisition software and the programs ImageJ and Excel. Otherwise, only commonly available cheap materials are required.
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| 8. |
- Blomqvist, Lisa A., 1978, et al.
(author)
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Proteomic analysis of highly purified prolamellar bodies reveals their significance in chloroplast development
- 2008
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 96:1, s. 37-50
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Journal article (peer-reviewed)abstract
- The prolamellar body (PLB) proteome of dark-grown wheat leaves was characterized. PLBs are formed not only in etioplasts but also in chloroplasts in young developing leaves during the night, yet their function is not fully understood. Highly purified PLBs were prepared from 7-day-old dark-grown leaves and identified by their spectral properties as revealed by low-temperature fluorescence spectroscopy. The PLB preparation had no contamination of extra-plastidal proteins, and only two envelope proteins were found. The PLB proteome was analysed by a combination of 1-D SDS-PAGE and nano-LC FTICR MS. The identification of chlorophyll synthase in the PLB fraction is the first time this enzyme protein was found in extracts of dark-grown plants. This finding is in agreement with its previous localization to PLBs using activity studies. NADPH:protochlorophyllide oxidoreductase A (PORA), which catalyses the reduction of protochlorophyllide to chlorophyllide, dominates the proteome of PLBs. Besides the identification of the PORA protein, the PORB protein was identified for the first time in dark-grown wheat. Altogether 64 unique proteins, representing pigment biosynthesis, photosynthetic light reaction, Calvin cycle proteins, chaperones and protein synthesis, were identified. The in number of proteins' largest group was the one involved in photosynthetic light reactions. This fact strengthens the assumption that the PLB membranes are precursors to the thylakoids and used for the formation of the photosynthetic membranes during greening. The present work is important to enhance our understanding of the significance of PLBs in chloroplast development.
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| 9. |
- Bossmann, B, et al.
(author)
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Screening of chlorina mutants of barley (Hordeum vulgare L.) with antibodies against light-harvesting proteins of PS I and PS II : Absence of specific antenna proteins
- 1997
-
In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 52:2, s. 127-136
-
Journal article (peer-reviewed)abstract
- Twenty-three chlorina (clo) mutants from the barley mutant collection of the Carlsberg Laboratory, Copenhagen, were tested for the presence of the four light-harvesting chlorophyll (Chl) a/b-binding proteins (LHC) of Photosystem I (Lhcal-4) and the PS II antenna proteins Lhcb1-3 (LHC II), Lhcb4-6 (CP29, CP26, CP24) and PsbS (CP22) using monospecific and monoclonal antibodies. Mutants allelic to barley mutant clo-f2, impaired in Chi b synthesis, provided evidence that Lhca4, Lhcb1 and Lhcb6 are unstable in the absence of Chi b, and the accumulation of Lhcb2, Lhcb3 and Lhcb4 is also impaired. Mutants at the locus chlorina-a (clo-a(117), clo-a(126) and clo-a(134)) lack or have only trace amounts of Lhca1, Lhca4, Lhcb1 and Lhcb3, whereas a mutant at the locus chlorina-b (clo-b(125)) had reduced amounts of all Lhca proteins. These two mutations could have an effect in protein import or assembly. Evidence is presented that Lhcb5 is the innermost LHC protein of PS II, and that Lhca1 and Lhca4, which have been supposed to be intimately associated in the LHCI-730 complex, can accumulate independently of each other. 77 K fluorescence emission spectra taken from leaves of clo-f2(101), clo-a(126) and clo-b(125) indicate that chlorophyll(s) emitting at 742 nm are coupled to the presence of Lhca4 that is bound to the reaction centre, and those emitting around 730 nm are located on Lhca1.
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| 10. |
- Buapet, Pimchanok, et al.
(author)
-
The role of O-2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L.
- 2016
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 129:1, s. 59-69
-
Journal article (peer-reviewed)abstract
- This study investigates the role of O-2 as an electron acceptor alternative to CO2 in photosynthesis of the common marine angiosperm Zostera marina L. Electron transport rates (ETRs) and non-photochemical quenching (NPQ) of Z. marina were measured under saturating irradiance in synthetic seawater containing 2.2 mM DIC and no DIC with different O-2 levels (air-equilibrated levels, 3 % of air equilibrium and restored air-equilibrated levels). Lowering O-2 did not affect ETR when DIC was provided, while it caused a decrease in ETR and an increase in NPQ in DIC-free media, indicating that O-2 acted as an alternative electron acceptor under low DIC. The ETR and NPQ as a function of irradiance were subsequently assessed in synthetic seawater containing (1) 2.2 mM DIC, air-equilibrated O-2; (2) saturating CO2, no O-2; and (3) no DIC, air-equilibrated O-2. These treatments were combined with glycolaldehyde pre-incubation. Glycolaldehyde caused a marked decrease in ETR in DIC-free medium, indicating significant electron flow supported by photorespiration. Combining glycolaldehyde with O-2 depletion completely suppressed ETR suggesting the operation of the Mehler reaction, a possibility supported by the photosynthesis-dependent superoxide production. However, no notable effect of suppressing the Mehler reaction on NPQ was observed. It is concluded that during DIC-limiting conditions, such as those frequently occurring in the habitats of Z. marina, captured light energy exceeds what is utilised for the assimilation of available carbon, and photorespiration is a major alternative electron acceptor, while the contribution of the Mehler reaction is minor.
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| 11. |
- Böddi, Béla, et al.
(author)
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Tissue specific protochlorophyll(ide) forms in dark-forced shoots of grapevine (Vitis vinifera L.)
- 2004
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 82:2, s. 141-150
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Journal article (peer-reviewed)abstract
- Cuttings of grapevine (Vitis vinifera L. cv. Chardonnay) were dark-forced at least three weeks. Pigment contents, 77 K fluorescence emission and excitation spectra of the leaves, petioles and stems and transmission electron micrographs of the etioplasts from leaves and the chlorenchyma tissues of the stems were analysed. The dark-grown leaves and stems contained 8 to 10 and 3 to 5 mug/g fresh weight protochlorophyllide and its esters, respectively. HPLC analysis showed that the molar ratio of the unesterified and esterified pigments was 7:3 in the shoot developed in darkness. The dark-forced leaves contained carotenoids identified as: neoxanthin, violaxanthin, antheraxanthin, lutein and beta-carotene. Detailed analyses of the fluorescence spectra proved that all tissues of the dark-forced shoots had protochlorophyllide or protochlorophyll forms with emission maxima at 628, 636, 644, 655 and 669 nm. The 628 and 636 nm emitting forms were present in all parts of the dark-forced shoot, but dominated in the stems, which may indicate an organ specificity of the etioplast development. Variations in the distribution of the pigment forms were even found in the different tissues of the stem. The subepidermal layers were more abundant in the 655 nm form than the parenchyma cells of the inner part of the cortex and the pith. In the latter cells, the plastid differentiation stopped in intermediary stages between proplastids and etioplasts. The plastids in the subepidermal layers had developed prolamellar body structures, which were similar to those of etiolated leaves. The results highlight the importance of organ- and tissue specificity of plastid differentiation for chlorophyll biosynthesis and greening of different plant organs.
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| 12. |
- Campbell, D, et al.
(author)
-
Two forms of the photosystem II D1 protein alter energy dissipation and state transitions in the cyanobacterium Synechococcus sp PCC 7942
- 1996
-
In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 47:2, s. 131-144
-
Journal article (peer-reviewed)abstract
- Synechococcus sp. PCC 7942 (Anacystis nidulans R2) contains two forms of the Photosystem II reaction centre protein D1, which differ in 25 of 360 amino acids. D1:1 predominates under low light hut is transiently replaced by D1:2 upon shifts to higher light. Mutant cells containing only D1:1 have lower photochemical energy capture efficiency and decreased resistance to photoinhibition, compared to cells containing D1:2. We show that when dark-adapted or under low to moderate light, cells with D1:1 have higher non-photochemical quenching of PS II fluorescence (higher q(N)) than do cells with D1:2. This is reflected in the 77 K chlorophyll emission spectra, with lower Photosystem II fluorescence at 697-698 nm in cells containing D1:1 than in cells with D1:2. This difference in quenching of Photosystem II fluorescence occurs upon excitation of both chlorophyll at 435 nm and phycobilisomes at 570 nm. Measurement of time-resolved room temperature fluorescence shows that Photosystem II fluorescence related to charge stabilization is quenched more rapidly in cells containing D1:1 than in those with D1:2. Cells containing D1:1 appear generally shifted towards State II, with PS II down-regulated, while cells with D1:2 tend towards State I. In these cyanobacteria electron transport away from PS II remains non-saturated even under photoinhibitory levels of light. Therefore, the higher activity of D1:2 Photosystem II centres may allow more rapid photochemical dissipation of excess energy into the electron transport chain. D1:1 confers capacity for extreme State II which may be of benefit under low and variable light.
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| 13. |
- Chow, Wah Soon, et al.
(author)
-
A tribute to Robert John Porra (august 7, 1931–may 16, 2019)
- 2021
-
In: Photosynthesis Research. - : Springer Nature. - 0166-8595 .- 1573-5079. ; 147:2, s. 125-130
-
Journal article (peer-reviewed)abstract
- Robert John Porra (7.8.1931–16.5.2019) is probably best known for his substantial practical contributions to plant physiology and photosynthesis by addressing the problems of both the accurate spectroscopic estimation and the extractability of chlorophylls in many organisms. Physiological data and global productivity estimates, in particular of marine primary productivity, are often quoted on a chlorophyll basis. He also made his impact by work on all stages of tetrapyrrole biosynthesis: he proved the C5 pathway to chlorophylls, detected an alternative route to protoporphyrin in anaerobes and the different origin of the oxygen atoms in anaerobes and aerobes. A brief review of his work is supplemented by personal memories of the authors.
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| 14. |
- Chow, Wah Soon, et al.
(author)
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Photoinactivation of photosystem II in leaves
- 2005
-
In: Photosynthesis Research. - Dordrecht : Springer. - 0166-8595 .- 1573-5079. ; 84:1-3, s. 35-41
-
Journal article (peer-reviewed)abstract
- Photoinactivation of Photosystem II (PS II), the light-induced loss of ability to evolve oxygen, inevitably occurs under any light environment in nature, counteracted by repair. Under certain conditions, the extent of photoinactivation of PS II depends on the photon exposure (light dosage, x), rather than the irradiance or duration of illumination per se, thus obeying the law of reciprocity of irradiance and duration of illumination, namely, that equal photon exposure produces an equal effect. If the probability of photoinactivation (p) of PS II is directly proportional to an increment in photon exposure (p = kDeltax, where k is the probability per unit photon exposure), it can be deduced that the number of active PS II complexes decreases exponentially as a function of photon exposure: N = Noexp(-kx). Further, since a photon exposure is usually achieved by varying the illumination time (t) at constant irradiance (I), N = Noexp(-kI t), i.e., N decreases exponentially with time, with a rate coefficient of photoinactivation kI, where the product kI is obviously directly proportional to I. Given that N = Noexp(-kx), the quantum yield of photoinactivation of PS II can be defined as -dN/dx = kN, which varies with the number of active PS II complexes remaining. Typically, the quantum yield of photoinactivation of PS II is ca. 0.1micromol PS II per mol photons at low photon exposure when repair is inhibited. That is, when about 10(7) photons have been received by leaf tissue, one PS II complex is inactivated. Some species such as grapevine have a much lower quantum yield of photoinactivation of PS II, even at a chilling temperature. Examination of the longer-term time course of photoinactivation of PS II in capsicum leaves reveals that the decrease in N deviates from a single-exponential decay when the majority of the PS II complexes are inactivated in the absence of repair. This can be attributed to the formation of strong quenchers in severely-photoinactivated PS II complexes, able to dissipate excitation energy efficiently and to protect the remaining active neighbours against damage by light.
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| 15. |
- Chow, Wah Soon, et al.
(author)
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Quantifying and monitoring functional photosystem II and the stoichiometry of the two photosystems in leaf segments : approaches and approximations
- 2012
-
In: Photosynthesis Research. - Dordrecht : Springer. - 0166-8595 .- 1573-5079. ; 113:1-3, s. 63-74
-
Research review (peer-reviewed)abstract
- Given its unique function in light-induced water oxidation and its susceptibility to photoinactivation during photosynthesis, photosystem II (PS II) is often the focus of studies of photosynthetic structure and function, particularly in environmental stress conditions. Here we review four approaches for quantifying or monitoring PS II functionality or the stoichiometry of the two photosystems in leaf segments, scrutinizing the approximations in each approach. (1) Chlorophyll fluorescence parameters are convenient to derive, but the information-rich signal suffers from the localized nature of its detection in leaf tissue. (2) The gross O-2 yield per single-turnover flash in CO2-enriched air is a more direct measurement of the functional content, assuming that each functional PS II evolves one O-2 molecule after four flashes. However, the gross O-2 yield per single-turnover flash (multiplied by four) could over-estimate the content of functional PS II if mitochondrial respiration is lower in flash illumination than in darkness. (3) The cumulative delivery of electrons from PS II to P700(+) (oxidized primary donor in PS I) after a flash is added to steady background far-red light is a whole-tissue measurement, such that a single linear correlation with functional PS II applies to leaves of all plant species investigated so far. However, the magnitude obtained in a simple analysis (with the signal normalized to the maximum photo-oxidizable P700 signal), which should equal the ratio of PS II to PS I centers, was too small to match the independently-obtained photosystem stoichiometry. Further, an under-estimation of functional PS II content could occur if some electrons were intercepted before reaching PS I. (4) The electrochromic signal from leaf segments appears to reliably quantify the photosystem stoichiometry, either by progressively photoinactivating PS II or suppressing PS I via photo-oxidation of a known fraction of the P700 with steady far-red light. Together, these approaches have the potential for quantitatively probing PS II in vivo in leaf segments, with prospects for application of the latter two approaches in the field.
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| 16. |
- Cisek, Richard, et al.
(author)
-
Optical microscopy in photosynthesis
- 2009
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 102:2-3, s. 111-141
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Research review (peer-reviewed)abstract
- Emerging as well as the most frequently used optical microscopy techniques are reviewed and image contrast generation methods in a microscope are presented, focusing on the nonlinear contrasts such as harmonic generation and multiphoton excitation fluorescence. Nonlinear microscopy presents numerous advantages over linear microscopy techniques including improved deep tissue imaging, optical sectioning, and imaging of live unstained samples. Nonetheless, with the exception of multiphoton excitation fluorescence, nonlinear microscopy is in its infancy, lacking protocols, users and applications; hence, this review focuses on the potential of nonlinear microscopy for studying photosynthetic organisms. Examples of nonlinear microscopic imaging are presented including isolated light-harvesting antenna complexes from higher plants, starch granules, chloroplasts, unicellular alga Chlamydomonas reinhardtii, and cyanobacteria Leptolyngbya sp. and Anabaena sp. While focusing on nonlinear microscopy techniques, second and third harmonic generation and multiphoton excitation fluorescence microscopy, other emerging nonlinear imaging modalities are described and several linear optical microscopy techniques are reviewed in order to clearly describe their capabilities and to highlight the advantages of nonlinear microscopy.
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| 17. |
- Conlan, Brendon l, et al.
(author)
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Thomas John Wydrzynski (8 July 1947-16 March 2018)
- 2019
-
In: Photosynthesis Research. - : Springer Netherlands. - 0166-8595 .- 1573-5079. ; 140:3, s. 253-261
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Journal article (peer-reviewed)abstract
- With this Tribute, we remember and honor Thomas John (Tom) Wydrzynski. Tom was a highly innovative, independent and committed researcher, who had, early in his career, defined his life-long research goal. He was committed to understand how Photosystem II produces molecular oxygen from water, using the energy of sunlight, and to apply this knowledge towards making artificial systems. In this tribute, we summarize his research journey, which involved working on soft money' in several laboratories around the world for many years, as well as his research achievements. We also reflect upon his approach to life, science and student supervision, as we perceive it. Tom was not only a thoughtful scientist that inspired many to enter this field of research, but also a wonderful supervisor and friend, who is deeply missed (see footnote*).
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| 18. |
- Conlan, Brendon, et al.
(author)
-
Thomas John Wydrzynski (8 July 1947–16 March 2018)
- 2019
-
In: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 140:3, s. 253-261
-
Journal article (pop. science, debate, etc.)abstract
- With this Tribute, we remember and honor Thomas John (Tom) Wydrzynski. Tom was a highly innovative, independent and committed researcher, who had, early in his career, defined his life-long research goal. He was committed to understand how Photosystem II produces molecular oxygen from water, using the energy of sunlight, and to apply this knowledge towards making artificial systems. In this tribute, we summarize his research journey, which involved working on 'soft money' in several laboratories around the world for many years, as well as his research achievements. We also reflect upon his approach to life, science and student supervision, as we perceive it. Tom was not only a thoughtful scientist that inspired many to enter this field of research, but also a wonderful supervisor and friend, who is deeply missed (see footnote*).
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| 19. |
- Dau, Holger, et al.
(author)
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Three overlooked photosynthesis papers of Otto Warburg (1883-1970), published in the 1940s in German and in Russian, on light-driven water oxidation coupled to benzoquinone reduction
- 2021
-
In: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 149:3, s. 259-264
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Journal article (peer-reviewed)abstract
- After a brief background on Otto Heinrich Warburg (1883–1970), and some of his selected research, we provide highlights, in English, of three of his papers in the 1940s—unknown to many as they were not originally published in English. They are: two brief reports on Photosynthesis, with Wilhelm Lüttgens, originally published in German, in 1944: ‘Experiment on assimilation of carbonic acid’; and ‘Further experiments on carbon dioxide assimilation’. This is followed by a regular paper, originally published in Russian, in 1946: ‘The photochemical reduction of quinone in green granules’. Since the 1944 reports discussed here are very short, their translations are included in the Appendix, but that of the 1946 paper is provided in the Supplementary Material. In all three reports, Warburg provides the first evidence for and elaborates on light-driven water oxidation coupled to reduction of added benzoquinone. These largely overlooked studies of Warburg are in stark contrast to Warburg’s well-known error in assigning the origin of the photosynthetically formed dioxygen to carbonate.
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| 20. |
-
Evolution of the Z-scheme of photosynthesis : a perspective
- 2017
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In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 133:1-3, s. 5-15
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Journal article (peer-reviewed)abstract
- The concept of the Z-scheme of oxygenic photosynthesis is in all the textbooks. However, its evolution is not. We focus here mainly on some of the history of its biophysical aspects. We have arbitrarily divided here the 1941-2016 period into three sub-periods: (a) Origin of the concept of two light reactions: first hinted at, in 1941, by James Franck and Karl Herzfeld; described and explained, in 1945, by Eugene Rabinowitch; and a clear hypothesis, given in 1956 by Rabinowitch, of the then available cytochrome experiments: one light oxidizing it and another reducing it; (b) Experimental discovery of the two light reactions and two pigment systems and the Z-scheme of photosynthesis: Robert Emerson's discovery, in 1957, of enhancement in photosynthesis when two light beams (one in the far-red region, and the other of shorter wavelengths) are given together than when given separately; and the 1960 scheme of Robin Hill & Fay Bendall; and (c) Evolution of the many versions of the Z-Scheme: Louis Duysens and Jan Amesz's 1961 experiments on oxidation and reduction of cytochrome f by two different wavelengths of light, followed by the work of many others for more than 50 years.
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| 21. |
- FALK, S, et al.
(author)
-
CHANGES IN PHOTOSYSTEM-II FLUORESCENCE IN CHLAMYDOMONAS-REINHARDTII EXPOSED TO INCREASING LEVELS OF IRRADIANCE IN RELATIONSHIP TO THE PHOTOSYNTHETIC RESPONSE TO LIGHT
- 1992
-
In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 31:1, s. 31-40
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Journal article (peer-reviewed)abstract
- The effects of a 60 min exposure to photosynthetic photon flux densities ranging from 300 to 2200-mu-mol m-2 s-1 on the photosynthetic light response curve and on PS II heterogeneity as reflected in chlorophyll a fluorescence were investigated using the unicellular green alga Chlamydomonas reinhardtii. It was established that exposure to high light acts at three different regulatory or inhibitory levels; 1) regulation occurs from 300 to 780-mu-mol m-2 s-1 where total amount of PS II centers and the shape of the light response curve is not significantly changed, 2) a first photoinhibitory range above 780 up to 1600-mu-mol m-2 s-1 where a progressive inhibition of the quantum yield and the rate of bending (convexity) of the light response curve can be related to the loss of Q(B)-reducing centers and 3) a second photoinhibitory range above 1600-mu-mol m-2 s-1 where the rate of light saturated photosynthesis also decreases and convexity reaches zero. This was related to a particularly large decrease in PS II(alpha) centers and a large increase in spill-over in energy to PS I.
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| 22. |
- Govindjee, Govindjee, et al.
(author)
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David (Dave) Charles Fork (1929–2020) : a gentle human being, a great experimenter, and a passionate researcher
- 2023
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In: Photosynthesis Research. - : Springer Netherlands. - 0166-8595 .- 1573-5079. ; 155:1, s. 107-125
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Journal article (peer-reviewed)abstract
- We provide here an overview of the remarkable life and outstanding research of David (Dave) Charles Fork (March 4, 1929–December 13, 2021) in oxygenic photosynthesis. In the words of the late Jack Edgar Myers, he was a top ‘photosynthetiker’. His research dealt with novel findings on light absorption, excitation energy distribution, and redistribution among the two photosystems, electron transfer, and their relation to dynamic membrane change as affected by environmental changes, especially temperature. David was an attentive listener and a creative designer of experiments and instruments, and he was also great fun to work with. He is remembered here by his family, coworkers, and friends from around the world including Australia, France, Germany, Japan, Sweden, Israel, and USA.
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| 23. |
- Hallin, Erik Ingmar, et al.
(author)
-
Molecular studies on structural changes and oligomerisation of violaxanthin de-epoxidase associated with the pH-dependent activation
- 2016
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 129:1, s. 29-41
-
Journal article (peer-reviewed)abstract
- Violaxanthin de-epoxidase (VDE) is a conditionally soluble enzyme located in the thylakoid lumen and catalyses the conversion of violaxanthin to antheraxanthin and zeaxanthin, which are located in the thylakoid membrane. These reactions occur when the plant or algae are exposed to saturating light and the zeaxanthin formed is involved in the process of non-photochemical quenching that protects the photosynthetic machinery during stress. Oversaturation by light results in a reduction of the pH inside the thylakoids, which in turn activates VDE and the de-epoxidation of violaxanthin. To elucidate the structural events responsible for the pH-dependent activation of VDE, full length and truncated forms of VDE were studied at different pH using circular dichroism (CD) spectroscopy, crosslinking and small angle X-ray scattering (SAXS). CD spectroscopy showed the formation of α-helical coiled-coil structure, localised in the C-terminal domain. Chemical crosslinking of VDE showed that oligomers were formed at low pH, and suggested that the position of the N-terminal domain is located near the opening of lipocalin-like barrel, where violaxanthin has been predicted to bind. SAXS was used to generate models of monomeric VDE at high pH and also a presumably dimeric structure of VDE at low pH. For the dimer, the best fit suggests that the interaction is dominated by one of the domains, preferably the C-terminal domain due to the lost ability to oligomerise at low pH, shown in earlier studies, and the predicted formation of coiled-coil structure.
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| 24. |
- Hallin, Erik, et al.
(author)
-
Violaxanthin de-epoxidase disulphides and their role in activity and thermal stability.
- 2015
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 124:2, s. 191-198
-
Journal article (peer-reviewed)abstract
- Violaxanthin de-epoxidase (VDE) catalyses the conversion of violaxanthin to zeaxanthin at the lumen side of the thylakoids during exposure to intense light. VDE consists of a cysteine-rich N-terminal domain, a lipocalin-like domain and a negatively charged C-terminal domain. That the cysteines are important for the activity of VDE is well known, but in what way is less understood. In this study, wild-type spinach VDE was expressed in E. coli as inclusion bodies, refolded and purified to give a highly active and homogenous preparation. The metal content (Fe, Cu, Ni, Mn, Co and Zn) was lower than 1 mol% excluding a metal-binding function of the cysteines. To investigate which of the 13 cysteines that could be important for the function of VDE, we constructed mutants where the cysteines were replaced by serines, one by one. For 12 out of 13 mutants the activity dropped by more than 99.9 %. A quantification of free cysteines showed that only the most N-terminal of these cysteines was in reduced form in the native VDE. A disulphide pattern in VDE of C9-C27, C14-C21, C33-C50, C37-C46, C65-C72 and C118-C284 was obtained after digestion of VDE with thermolysin followed by mass spectroscopy analysis of reduced versus non-reduced samples. The residual activity found for the mutants showed a variation that was consistent with the results obtained from mass spectroscopy. Reduction of the disulphides resulted in loss of a rigid structure and a decrease in thermal stability of 15 °C.
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| 25. |
- Haniewicz, Patrycja, et al.
(author)
-
Isolation of monomeric photosystem II that retains the subunit PsbS.
- 2013
-
In: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 118:3, s. 199-207
-
Journal article (peer-reviewed)abstract
- Photosystem II has been purified from a transplastomic strain of Nicotiana tabacum according to two different protocols. Using the procedure described in Piano et al. (Photosynth Res 106:221-226, 2010) it was possible to isolate highly active PSII composed of monomers and dimers but depleted in their PsbS protein content. A "milder" procedure than the protocol reported by Fey et al. (Biochim Biophys Acta 1777:1501-1509, 2008) led to almost exclusively monomeric PSII complexes which in part still bind the PsbS protein. This finding might support a role for PSII monomers in higher plants.
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| 26. |
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| 27. |
- Ho, Felix M.
(author)
-
Uncovering channels in photosystem II by computer modelling : current progress, future prospects, and lessons from analogous systems
- 2008
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 98:1-3, s. 503-522
-
Research review (peer-reviewed)abstract
- Even prior to the publication of the crystal structures for photosystem II (PSII), it had already been suggested that water, O-2 and H+ channels exist in PSII to achieve directed transport of these molecules, and to avoid undesirable side reactions. Computational efforts to uncover these channels and investigate their properties are still at early stages, and have so far only been based on the static PSII structure. The rationale behind the proposals for such channels and the computer modelling studies thus far are reviewed here. The need to take the dynamic protein into account is then highlighted with reference to the specific issues and techniques applicable to the simulation of each of the three channels. In particular, lessons are drawn from simulation studies on other protein systems containing similar channels.
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| 28. |
- HUNER, NPA, et al.
(author)
-
PHOTOSYNTHESIS, PHOTOINHIBITION AND LOW-TEMPERATURE ACCLIMATION IN COLD TOLERANT PLANTS
- 1993
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In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 37:1, s. 19-39
-
Journal article (peer-reviewed)abstract
- Cold acclimation requires adjustment to a combination of light and low temperature, conditions which are potentially photoinhibitory. The photosynthetic response of plants to low temperature is dependent upon time of exposure and the developmental history of the leaves. Exposure of fully expanded leaves of winter cereals to short-term, low temperature shifts inhibits whereas low temperature growth stimulates electron transport capacity and carbon assimilation. However, the photosynthetic response to low temperature is clearly species and cultivar dependent. Winter annuals and algae which actively grow and develop at low temperature and moderate irradiance acquire a resistance to irradiance 5- to 6-fold higher than their growth irradiance. Resistance to short-term photoinhibition (hours) in winter cereals is a reflection of the increased capacity to keep Q(A) oxidized under high light conditions and low temperature. This is due to an increased capacity for photosynthesis. These characteristics reflect photosynthetic acclimation to low growth temperature and can be used to predict the freezing tolerance of cereals. It is proposed that the enhanced photosynthetic capacity reflects an increased flux of fixed carbon through to sucrose in source tissue as a consequence of the combined effects of increased storage of carbohydrate as fructans in the vacuole of leaf mesophyll cells and an enhanced export to the crown due to its increased sink activity. Long-term exposure (months) of cereals to low temperature photoinhibition indicates that this reduction of photochemical efficiency of PS II represents a stable, long-term down regulation of PS II to match the energy requirements for CO2 fixation. Thus, photoinhibition in vivo should be viewed as the capacity of plants to adjust photosynthetically to the prevailing environmental conditions rather than a process which necessarily results in damage or injury to plants. Not all cold tolerant, herbaceous annuals use the same mechanism to acquire resistance to photoinhibition. In contrast to annuals and algae, overwintering evergreens become dormant during the cold hardening period and generally remain susceptible to photoinhibition. It is concluded that the photosynthetic response to low temperatures and susceptibility to photoinhibition are consequences of the overwintering strategy of the plant species.
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| 29. |
- Hussein, Rana, et al.
(author)
-
Evolutionary diversity of proton and water channels on the oxidizing side of photosystem II and their relevance to function
- 2023
-
In: Photosynthesis Research. - : Springer Nature. - 0166-8595 .- 1573-5079. ; 158:2, s. 91-107
-
Research review (peer-reviewed)abstract
- One of the reasons for the high efficiency and selectivity of biological catalysts arise from their ability to control the pathways of substrates and products using protein channels, and by modulating the transport in the channels using the interaction with the protein residues and the water/hydrogen-bonding network. This process is clearly demonstrated in Photosystem II (PS II), where its light-driven water oxidation reaction catalyzed by the Mn4CaO5 cluster occurs deep inside the protein complex and thus requires the transport of two water molecules to and four protons from the metal center to the bulk water. Based on the recent advances in structural studies of PS II from X-ray crystallography and cryo-electron microscopy, in this review we compare the channels that have been proposed to facilitate this mass transport in cyanobacteria, red and green algae, diatoms, and higher plants. The three major channels (O1, O4, and Cl1 channels) are present in all species investigated; however, some differences exist in the reported structures that arise from the different composition and arrangement of membrane extrinsic subunits between the species. Among the three channels, the Cl1 channel, including the proton gate, is the most conserved among all photosynthetic species. We also found at least one branch for the O1 channel in all organisms, extending all the way from Ca/O1 via the ‘water wheel’ to the lumen. However, the extending path after the water wheel varies between most species. The O4 channel is, like the Cl1 channel, highly conserved among all species while having different orientations at the end of the path near the bulk. The comparison suggests that the previously proposed functionality of the channels in T. vestitus (Ibrahim et al., Proc Natl Acad Sci USA 117:12624–12635, 2020; Hussein et al., Nat Commun 12:6531, 2021) is conserved through the species, i.e. the O1-like channel is used for substrate water intake, and the tighter Cl1 and O4 channels for proton release. The comparison does not eliminate the potential role of O4 channel as a water intake channel. However, the highly ordered hydrogen-bonded water wire connected to the Mn4CaO5 cluster via the O4 may strongly suggest that it functions in proton release, especially during the S0 → S1 transition (Saito et al., Nat Commun 6:8488, 2015; Kern et al., Nature 563:421–425, 2018; Ibrahim et al., Proc Natl Acad Sci USA 117:12624–12635, 2020; Sakashita et al., Phys Chem Chem Phys 22:15831–15841, 2020; Hussein et al., Nat Commun 12:6531, 2021).
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| 30. |
- Igamberdiev, A U, et al.
(author)
-
Decarboxylation of glycine contributes to carbon isotope fractionation in photosynthetic organisms
- 2001
-
In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 67:3, s. 177-184
-
Journal article (peer-reviewed)abstract
- Carbon isotope effects were investigated for the reaction catalyzed by the glycine decarboxylase complex (GDC; EC 2.1.2.10). Mitochondria isolated from leaves of pea (Pisum sativum L.) and spinach (Spinacia oleracea L.) were incubated with glycine, and the CO2 evolved was analyzed for the carbon isotope ratio (delta C-13). Within the range of parameters tested (temperature, pH, combination of cofactors NAD(+), ADP, pyridoxal 5-phosphate), carbon isotope shifts of CO2 relative to the C-1-carboxyl carbon of glycine varied from +14 parts per thousand to -7 parts per thousand. The maximum effect of cofactors was observed for NAD(+), the removal of which resulted in a strong C-12 enrichment of the CO2 evolved. This indicates the possibility of isotope effects with both positive and negative signs in the GDC reaction. The measurement of delta C-13 in the leaves of the GDC-deficient barley ( Hordeum vulgare L.) mutant (LaPr 87/30) plants indicated that photorespiratory carbon isotope fractionation, opposite in sign when compared to the carbon isotope effect during CO2 photoassimilation, takes place in vivo. Thus the key reaction of photorespiration catalyzed by GDC, together with the key reaction of CO2 fixation catalyzed by ribulose-1,5-bisphosphate carboxylase, both contribute to carbon isotope fractionation in photosynthesis.
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| 31. |
- Ishikawa, Yasuo, et al.
(author)
-
Functional analysis of the PsbP-like protein (sll1418) in Synechocystis sp PCC 6803
- 2005
-
In: Photosynthesis Research. - Dordrecht : Springer. - 0166-8595 .- 1573-5079. ; 84:1-3, s. 257-262
-
Journal article (peer-reviewed)abstract
- A recent proteomic analysis of the thylakoid lumen of Arabidopsis thaliana revealed the presence of several PsbP-like proteins, and a homologue to this gene family was detected in the genome of the cyanobacterium Synechocystis sp. PCC 6803 (Schubert M, Petersson UA, Haas BJ, Funk C, Schroder WP, Kieselbach T (2002) J Biol Chem 277, 8354-8365). Using a peptide-directed antibody against this cyanobacterial PsbP-like protein (sll1418) we could show that it was localized in the thylakoid membrane and associated with Photosystem II. While salt washes did not remove the PsbP-like protein from the thylakoid membrane, it was partially lost during the detergent-based isolation of PSII membrane fractions. In total cell extracts this protein is present in the same amount as the extrinsic PsbO protein. We did not see any significant functional difference between the wild-type and a PsbP-like insertion mutant.
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| 32. |
- Ivanov, A. G., et al.
(author)
-
Implications of alternative electron sinks in increased resistance of PSII and PSI photochemistry to high light stress in cold-acclimated Arabidopsis thaliana
- 2012
-
In: Photosynthesis Research. - Dordrecht : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 113:1-3, s. 191-206
-
Journal article (peer-reviewed)abstract
- Exposure of control (non-hardened) Arabidopsis leaves to high light stress at 5 A degrees C resulted in a decrease of both photosystem II (PSII) (45 %) and Photosystem I (PSI) (35 %) photochemical efficiencies compared to non-treated plants. In contrast, cold-acclimated (CA) leaves exhibited only 35 and 22 % decrease of PSII and PSI photochemistry, respectively, under the same conditions. This was accompanied by an accelerated rate of P700(+) re-reduction, indicating an up-regulation of PSI-dependent cyclic electron transport (CET). Interestingly, the expression of the NDH-H gene and the relative abundance of the Ndh-H polypeptide, representing the NDH-complex, decreased as a result of exposure to low temperatures. This indicates that the NDH-dependent CET pathway cannot be involved and the overall stimulation of CET in CA plants is due to up-regulation of the ferredoxin-plastoquinone reductase, antimycin A-sensitive CET pathway. The lower abundance of NDH complex also implies lower activity of the chlororespiratory pathway in CA plants, although the expression level and overall abundance of the other well-characterized component involved in chlororespiration, the plastid terminal oxidase (PTOX), was up-regulated at low temperatures. This suggests increased PTOX-mediated alternative electron flow to oxygen in plants exposed to low temperatures. Indeed, the estimated proportion of O-2-dependent linear electron transport not utilized in carbon assimilation and not directed to photorespiration was twofold higher in CA Arabidopsis. The possible involvement of alternative electron transport pathways in inducing greater resistance of both PSII and PSI to high light stress in CA plants is discussed.
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| 33. |
- Ivanov, Alexander G., et al.
(author)
-
Photosystem II reaction centre quenching : mechanisms and physiological role
- 2008
-
In: Photosynthesis Research. - : Springer Netherlands. - 0166-8595 .- 1573-5079. ; 98:1-3, s. 565-574
-
Journal article (peer-reviewed)abstract
- Dissipation of excess absorbed light energy in eukaryotic photoautotrophs through zeaxanthin- and ΔpH-dependent photosystem II antenna quenching is considered the major mechanism for non-photochemical quenching and photoprotection. However, there is mounting evidence of a zeaxanthin-independent pathway for dissipation of excess light energy based within the PSII reaction centre that may also play a significant role in photoprotection. We summarize recent reports which indicate that this enigma can be explained, in part, by the fact that PSII reaction centres can be reversibly interconverted from photochemical energy transducers that convert light into ATP and NADPH to efficient, non-photochemical energy quenchers that protect the photosynthetic apparatus from photodamage. In our opinion, reaction centre quenching complements photoprotection through antenna quenching, and dynamic regulation of photosystem II reaction centre represents a general response to any environmental condition that predisposes the accumulation of reduced QA in the photosystem II reaction centres of prokaryotic and eukaryotic photoautotrophs. Since the evolution of reaction centres preceded the evolution of light harvesting systems, reaction centre quenching may represent the oldest photoprotective mechanism.
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| 34. |
- Joliot, Pierre, et al.
(author)
-
In photosynthesis, oxygen comes from water: from a 1787 book for women by Monsieur De Fourcroy
- 2016
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 129:1, s. 105-107
-
Journal article (peer-reviewed)abstract
- It is now well established that the source ofoxygen in photosynthesis is water. The earliest suggestionpreviously known to us had come from Rene´ BernardWurmser (1930). Here, we highlight an earlier report byMonsieur De Fourcroy (1787), who had already discussedthe broad outlines of such a hypothesis in a book onChemistry written for women. We present here a freetranslation of a passage from this book, with the originaltext in French as an Appendix.
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| 35. |
- Kieselbach, Thomas, et al.
(author)
-
Proteomic analysis of the phycobiliprotein antenna of the cryptophyte alga Guillardia theta cultured under different light intensities
- 2018
-
In: Photosynthesis Research. - : Springer. - 0166-8595 .- 1573-5079. ; 135:1–3, s. 149-163
-
Journal article (peer-reviewed)abstract
- Plants and algae have developed various light-harvesting mechanisms for optimal delivery of excitation energy to the photosystems. Cryptophyte algae have evolved a novel soluble light-harvesting antenna utilizing phycobilin pigments to complement the membrane-intrinsic Chl a/c-binding LHC antenna. This new antenna consists of the plastid-encoded β-subunit, a relic of the ancestral phycobilisome, and a novel nuclear-encoded α-subunit unique to cryptophytes. Together, these proteins form the active α1β·α2β-tetramer. In all cryptophyte algae investigated so far, the α-subunits have duplicated and diversified into a large gene family. Although there is transcriptional evidence for expression of all these genes, the X-ray structures determined to date suggest that only two of the α-subunit genes might be significantly expressed at the protein level. Using proteomics, we show that in phycoerythrin 545 (PE545) of Guillardia theta, the only cryptophyte with a sequenced genome, all 20 α-subunits are expressed when the algae grow under white light. The expression level of each protein depends on the intensity of the growth light, but there is no evidence for a specific light-dependent regulation of individual members of the α-subunit family under the growth conditions applied. GtcpeA10 seems to be a special member of the α-subunit family, because it consists of two similar N- and C-terminal domains, which likely are the result of a partial tandem gene duplication. The proteomics data of this study have been deposited to the ProteomeXchange Consortium and have the dataset identifiers PXD006301 and 10.6019/PXD006301.
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| 36. |
- Krausz, E, et al.
(author)
-
Assignment of the low-temperature fluorescence in oxygen-evolving Photosystem II
- 2005
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 84:1-3, s. 193-199
-
Journal article (peer-reviewed)abstract
- Low-temperature absorption and fluorescence spectra of fully active cores and membrane-bound PS II preparations are compared. Detailed temperature dependence of fluorescence spectra between 5 and 70 K are presented as well as 1.7-K fluorescence line-narrowed (FLN) spectra of cores, confirming that PS II emission is composite. Spectra are compared to those reported for LHCII, CP43, CP47 and D1/D2/cytb(559) subunits of PS II. A combination of subunit spectra cannot account for emission of active PS II. The complex temperature dependence of PS II fluorescence is interpretable by noting that excitation transfer from CP43 and CP47 to the reaction centre is slow, and strongly dependent on the precise energy at which a 'slow-transfer' pigment in CP43 or CP47 is located within its inhomogeneous distribution. PS II fluorescence arises from CP43 and CP47 'slow-transfer' states, convolved by this dependence. At higher temperatures, thermally activated excitation transfer to the PS II charge-separating system bypasses such bottlenecks. As the charge-separating state of active PS II absorbs at >700 nm, PS II emission in the 680-700 nm region is unlikely to arise from reaction centre pigments. PS II emission at physiological temperatures is discussed in terms of these results.
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| 37. |
- Krausz, Elmars, et al.
(author)
-
Spectral characteristics of PS II reaction centres: as isolated preparations and when integral to PS II core complexes
- 2008
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 98:1-3, s. 207-217
-
Journal article (peer-reviewed)abstract
- The discovery that the native PS II enzyme undergoes charge separation via an absorption extending to 730 nm has led us to re-examine the low-temperature absorption spectra of Nanba-Satoh PS II reaction centre preparations with particular focus on the long wavelength region. It is shown that these preparations do not exhibit absorption in the 700-730 nm region at 1.7 K. Absorption in the Nanba-Satoh type preparations analogous to the 'red tail' as observed in functional PS II core complexes is likely shifted to higher energy by >20 nm. Spectral changes associated with the stable reduction of pheo(a) in chemically treated reaction centre preparations are also revisited. Dithionite treatment of PS II preparations in the dark leads to changes of pigment-pigment and/or pigment protein interactions, as evidenced by changes in absorption and CD spectra. Absorption and CD changes associated with stable Pheo(D1) photo-reduction in PS II core complexes and Nanba-Satoh preparations are compared. For Nanba-Satoh preparations, Q(y) bleaches are similar to 39X broader than in PS II core complexes and are blue-shifted by similar to 4 nm. These data are discussed in terms of current models of PS II, and suggest a need to consider protein-induced changes of some electronic properties of reaction centre pigments.
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| 38. |
- Kufryk, Galyna, et al.
(author)
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Association of small CAB-like proteins (SCPs) of Synechocystis sp. PCC 6803 with Photosystem II
- 2008
-
In: Photosynthesis Research. - : SpringerLink. - 0166-8595 .- 1573-5079. ; 95:2/3, s. 135-145
-
Journal article (peer-reviewed)abstract
- The cyanobacterial small CAB-like proteins (SCPs) are one-helix proteins with compelling similarity to the first and third transmembrane helix of proteins belonging to the CAB family of light-harvesting complex proteins in plants. The SCP proteins are transiently expressed at high light intensity and other stress conditions but their exact function remains largely unknown. Recently we showed association of ScpD with light-stressed, monomeric Photosystem II in Synechocystis sp. PCC 6803 (Yao et al. J Biol Chem 282:267-276, 2007). Here we show that ScpB associates with Photosystem II at normal growth conditions. Moreover, upon introduction of a construct into Synechocystis so that ScpB is expressed continuously under normal growth conditions, ScpE was detected under non-stressed conditions as well, and was copurified with tagged ScpB and Photosystem II. We also report on a one-helix protein, Slr1544, that is somewhat similar to the SCPs and whose gene is cotranscribed with that of ScpD; Slr1544 is another member of the extended light-harvesting-like (Lil) protein family, and we propose to name it LilA.
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| 39. |
- Kulik, L, et al.
(author)
-
Pulse EPR, 55Mn-ENDOR and ELDOR-detected NMR of the S2-state of the oxygen evolving complex in Photosystem II
- 2005
-
In: Photosynthesis Research. - : SPRINGER. - 0166-8595 .- 1573-5079. ; 84:1-3, s. 347-353
-
Journal article (peer-reviewed)abstract
- Pulse EPR, Mn-55-ENDOR and ELDOR-detected NMR experiments were performed on the S-2-state of the oxygen-evolving complex from spinach Photosystem II. The novel technique of random acquisition in ENDOR was used to suppress heating artefacts. Our data unambiguously shows that four Mn ions have significant hyperfine coupling constants. Numerical simulation of the Mn-55-ENDOR spectrum allowed the determination of the principal values of the hyperfine interaction tensors for all four Mn ions of the oxygen-evolving complex. The results of our Mn-55-ENDOR experiments are in good agreement with previously published data [Peloquin JM et al. (2000) J Am Chem Soc 122: 10926-10942]. For the first time ELDOR-detected NMR was applied to the S-2-state and revealed a broad peak that can be simulated numerically with the same parameters that were used for the simulation of the Mn-55-ENDOR spectrum. This provides strong independent support for the assigned hyperfine parameters.
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| 40. |
- Kurepin, Leonid V., et al.
(author)
-
Stress-related hormones and glycinebetaine interplay in protection of photosynthesis under abiotic stress conditions
- 2015
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 126:2-3, s. 221-235
-
Research review (peer-reviewed)abstract
- Plants subjected to abiotic stresses such as extreme high and low temperatures, drought or salinity, often exhibit decreased vegetative growth and reduced reproductive capabilities. This is often associated with decreased photosynthesis via an increase in photoinhibition, and accompanied by rapid changes in endogenous levels of stress-related hormones such as abscisic acid (ABA), salicylic acid (SA) and ethylene. However, certain plant species and/or genotypes exhibit greater tolerance to abiotic stress because they are capable of accumulating endogenous levels of the zwitterionic osmolyte-glycinebetaine (GB). The accumulation of GB via natural production, exogenous application or genetic engineering, enhances plant osmoregulation and thus increases abiotic stress tolerance. The final steps of GB biosynthesis occur in chloroplasts where GB has been shown to play a key role in increasing the protection of soluble stromal and lumenal enzymes, lipids and proteins, of the photosynthetic apparatus. In addition, we suggest that the stress-induced GB biosynthesis pathway may well serve as an additional or alternative biochemical sink, one which consumes excess photosynthesis-generated electrons, thus protecting photosynthetic apparatus from overreduction. Glycinebetaine biosynthesis in chloroplasts is up-regulated by increases in endogenous ABA or SA levels. In this review, we propose and discuss a model describing the close interaction and synergistic physiological effects of GB and ABA in the process of cold acclimation of higher plants.
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| 41. |
- Lindquist, Emelie, et al.
(author)
-
Chloroplast vesicle transport
- 2018
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 138:3, s. 361-371
-
Research review (peer-reviewed)abstract
- Photosynthesis is a well-known process that has been intensively investigated, but less is known about the biogenesis of the thylakoid membrane that harbors the photosynthetic machinery. Thylakoid membranes are constituted by several components, the major ones being proteins and lipids. However, neither of these two are produced in the thylakoid membranes themselves but are targeted there by different mechanisms. The interior of the chloroplast, the stroma, is an aqueous compartment that prevents spontaneous transport of single lipids and/or membrane proteins due to their hydrophobicities. Thylakoid targeted proteins are encoded either in the nucleus or plastid, and thus some cross the envelope membrane before entering one of the identified thylakoid targeting pathways. However, the pathway for all thylakoid proteins is not known. Lipids are produced at the envelope membrane and have been proposed to reach the thylakoid membrane by different means: invaginations of the envelope membrane, direct contact sites between these membranes, or through vesicles. Vesicles have been observed in chloroplasts but not much is yet known about the mechanism or regulation of their formation. The question of whether proteins can also make use of vesicles as one mechanism of transport remains to be answered. Here we discuss the presence of vesicles in chloroplasts and their potential role in transporting lipids and proteins. We additionally discuss what is known about the proteins involved in the vesicle transport and the gaps in knowledge that remain to be filled.
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| 42. |
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| 43. |
- Lundin, Björn, et al.
(author)
-
Towards understanding the functional difference between the two PsbO isoforms in Arabidopsis thaliana-insights from phenotypic analyses of psbo knockout mutants
- 2008
-
In: Photosynthesis Research. - : Springer Science and Business Media LLC. - 0166-8595 .- 1573-5079. ; 98:1-3, s. 405-414
-
Journal article (peer-reviewed)abstract
- The extrinsic PsbO subunit of the water-oxidizing photosystem II (PSII) complex is represented by two isoforms in Arabidopsis thaliana, namely PsbO1 and PsbO2. Recent analyses of psbo1 and psbo2 knockout mutants have brought insights into their roles in photosynthesis and light stress. Here we analyzed the two psbo mutants in terms of PsbOs expression pattern, organization of PSII complexes and GTPase activity. Both PsbOs are present in wild-type plants, and their expression is mutually controlled in the mutants. Almost all PSII complexes are in the monomeric form not only in the psbo1 but also in the psbo2 mutant grown under high-light conditions. This results either from an enhanced susceptibility of PSII to photoinactivation or from malfunction of the repair cycle. Notably, the psbo1 mutant displays such problems even under growth-light conditions. These results together with the finding that PsbO2 has a threefold higher GTPase activity than PsbO1 have significance for the turnover of the PSII D1 subunit in Arabidopsis.
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| 44. |
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| 45. |
- Mamedov, Fikret, et al.
(author)
-
Influence of protein phosphorylation on the electron-transport properties of Photosystem II
- 2002
-
In: Photosynthesis Research. - 0166-8595 .- 1573-5079. ; 74:1, s. 61-72
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Journal article (peer-reviewed)abstract
- Many of the core proteins in Photosystem II (PS II) undergo reversible phosphorylation. It is known that protein phosphorylation controls the repair cycle of Photosystem II. However, it is not known how protein phosphorylation affects the partial electron transport reactions in PS II. Here we have applied variable fluorescence measurements and EPR spectroscopy to probe the status of the quinone acceptors, the Mn cluster and other electron transfer components in PS II with controlled levels of protein phosphorylation. Protein phosphorylation was induced in vivo by varying illumination regimes. The phosphorylation level of the D1 protein varied from 10 to 58% in PS II membranes isolated from pre-illuminated spinach leaves. The oxygen evolution and Q A- to Q B(Q B-) electron transfer measured by flash-induced fluorescence decay remained similar in all samples studied. Similar measurements in the presence of DCMU, which reports on the status of the donor side in PS II, also indicated that the integrity of the oxygen-evolving complex was preserved in PS II with different levels of D1 protein phosphorylation. With EPR spectroscopy we examined individual redox cofactors in PS II. Both the maximal amplitude of the charge separation reaction (measured as photo-accumulated pheophytin-) and the EPR signal from the Q A- Fe2+ complex were unaffected by the phosphorylation of the D1 protein, indicating that the acceptor side of PS II was not modified. Also the shape of the S2 state multiline signal was similar, suggesting that the structure of the Mn-cluster in Photosystem II did not change. However, the amplitude of the S2 multiline signal was reduced by 35% in PS II, where 58% of the D1 protein was phosphorylated, as compared to the S2 multiline in PS II, where only 10% of the D1 protein was phosphorylated. In addition, the fraction of low potential Cyt b559 was twice as high in phosphorylated PS II. Implications from these findings, were precise quantification of D1 protein phosphorylation is, for the first time, combined with high-resolution biophysical measurements, are discussed.
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- Messinger, Johannes, 1963-, et al.
(author)
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Warwick Hillier : a tribute
- 2014
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In: Photosynthesis Research. - : SPRINGER. - 0166-8595 .- 1573-5079. ; 122:1, s. 1-11
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Journal article (peer-reviewed)abstract
- Warwick Hillier (October 18, 1967-January 10, 2014) made seminal contributions to our understanding of photosynthetic water oxidation employing membrane inlet mass spectrometry and FTIR spectroscopy. This article offers a collection of historical perspectives on the scientific impact of Warwick Hillier's work and tributes to the personal impact his life and ideas had on his collaborators and colleagues.
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