| 1. |
|
|
| 2. |
- Damkjær, Jakob T, 1976-, et al.
(författare)
-
The photosystem II light-harvesting protein Lhcb3 affects the macrostructure of photosystem II and the rate of state transitions in Arabidopsis
- 2009
-
Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 21, s. 3245-3256
-
Tidskriftsartikel (refereegranskat)abstract
- The main trimeric light-harvesting complex of higher plants (LHCII) consists of three different Lhcb proteins (Lhcb1-3). We show that Arabidopsis thaliana T-DNA knockout plants lacking Lhcb3 (koLhcb3) compensate for the lack of Lhcb3 by producing increased amounts of Lhcb1 and Lhcb2. As in wild-type plants, LHCII-photosystem II (PSII) supercomplexes were present in Lhcb3 knockout plants (koLhcb3), and preservation of the LHCII trimers (M trimers) indicates that the Lhcb3 in M trimers has been replaced by Lhcb1 and/or Lhcb2. However, the rotational position of the M LHCII trimer was altered, suggesting that the Lhcb3 subunit affects the macrostructural arrangement of the LHCII antenna. The absence of Lhcb3 did not result in any significant alteration in PSII efficiency or qE type of nonphotochemical quenching, but the rate of transition from State 1 to State 2 was increased in koLhcb3, although the final extent of state transition was unchanged. The level of phosphorylation of LHCII was increased in the koLhcb3 plants compared with wild-type plants in both State 1 and State 2. The relative increase in phosphorylation upon transition from State 1 to State 2 was also significantly higher in koLhcb3. It is suggested that the main function of Lhcb3 is to modulate the rate of state transitions.
|
|
| 3. |
- Klionsky, Daniel J., et al.
(författare)
-
Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes
- 2008
-
Ingår i: Autophagy. - : Landes Bioscience. - 1554-8627 .- 1554-8635. ; 4:2, s. 151-175
-
Forskningsöversikt (refereegranskat)abstract
- Research in autophagy continues to accelerate,1 and as a result many new scientists are entering the field. Accordingly, it is important to establish a standard set of criteria for monitoring macroautophagy in different organisms. Recent reviews have described the range of assays that have been used for this purpose.2,3 There are many useful and convenient methods that can be used to monitor macroautophagy in yeast, but relatively few in other model systems, and there is much confusion regarding acceptable methods to measure macroautophagy in higher eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers of autophagosomes versus those that measure flux through the autophagy pathway; thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from fully functional autophagy that includes delivery to, and degradation within, lysosomes (in most higher eukaryotes) or the vacuole (in plants and fungi). Here, we present a set of guidelines for the selection and interpretation of the methods that can be used by investigators who are attempting to examine macroautophagy and related processes, as well as by reviewers who need to provide realistic and reasonable critiques of papers that investigate these processes. This set of guidelines is not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to verify an autophagic response.
|
|
| 4. |
- Kovacs, Krisztina, et al.
(författare)
-
Trichoderma atroviride mutants with enhanced production of cellulase and beta-glucosidase on pretreated willow
- 2008
-
Ingår i: Enzyme and Microbial Technology. - : Elsevier BV. - 0141-0229. ; 43:1, s. 48-55
-
Tidskriftsartikel (refereegranskat)abstract
- Trichoderma atroviride mutants were developed by using N-methyl-N'-nitro-N-nitrosoguanidine (NTG) treatment and UV-Iight followed by a semiquantitative plate clearing assay on Walseth-cellulose/agar plates. The parent strain of the mutants was an isolate from the Amazonas basin (TUB F-1505), whose identity was established by ITS 1 and 2 and tef1 gene sequence analysis. Strain F-1505 proved to be the most promising extracellular cellulase producer among 150 wild-type Trichoderma in a screening program performed in shake flask fermentation on pretreated willow. Reducing sugar content, soluble protein, filter paper cellulase activity (FPA), beta-glucosidase activity and endoglucanase activity of the fermentation broths of the mutant strains were measured in both shake flask and lab-scale fermenters and compared with Trichoderma reesei Rut C30. Also, hydrolytic capacities of fermentation supernatants of T reesei Rut C30, the parent strain (F-1505) and the best mutants were compared on pretreated willow as carbon source and hydrolysis substrate. The T atroviride mutants produced high levels of extracellular cellulases as well as beta-glucosidase, rendering the need for beta-glucosidase supplementation in hydrolysis of cellulose or pretreated willow unnecessary. On the contrary, beta-glucosidase supplementations were essential in order to obtain good glucose yields for all other cellulase preparations tested.
|
|
| 5. |
- Kovács, Laszlo, et al.
(författare)
-
Lack of the light-harvesting complex CP24 affects the structure and function of the grana membranes of higher plant chloroplasts.
- 2006
-
Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 18:11, s. 3106-20
-
Tidskriftsartikel (refereegranskat)abstract
- The photosystem II (PSII) light-harvesting antenna in higher plants contains a number of highly conserved gene products whose function is unknown. Arabidopsis thaliana plants depleted of one of these, the CP24 light-harvesting complex, have been analyzed. CP24-deficient plants showed a decrease in light-limited photosynthetic rate and growth, but the pigment and protein content of the thylakoid membranes were otherwise almost unchanged. However, there was a major change in the macroorganization of PSII within these membranes; electron microscopy and image analysis revealed the complete absence of the C2S2M2 light-harvesting complex II (LHCII)/PSII supercomplex predominant in wild-type plants. Instead, only C2S2 supercomplexes, which are deficient in the LHCIIb M-trimers, were found. Spectroscopic analysis confirmed the disruption of the wild-type macroorganization of PSII. It was found that the functions of the PSII antenna were disturbed: connectivity between PSII centers was reduced, and maximum photochemical yield was lowered; rapidly reversible nonphotochemical quenching was inhibited; and the state transitions were altered kinetically. CP24 is therefore an important factor in determining the structure and function of the PSII light-harvesting antenna, providing the linker for association of the M-trimer into the PSII complex, allowing a specific macroorganization that is necessary both for maximum quantum efficiency and for photoprotective dissipation of excess excitation energy.
|
|
