| 1. |
- Cain, Peter, et al.
(författare)
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A novel extended family of stromal thioredoxins
- 2009
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Ingår i: Plant Molecular Biology. - : Springer. - 0167-4412 .- 1573-5028. ; 70:3, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- Thioredoxins play key regulatory roles in chloroplasts by linking photosynthetic light reactions to a series of plastid functions. In addition to the established groups of thioredoxins, f, m, x, and y, novel plant thioredoxins were also considered to include WCRKC motif proteins, CDSP32, the APR proteins, the lilium proteins and HCF164. Despite their important roles, the subcellular locations of many novel thioredoxins has remained unknown. Here, we report a study of their subcellular location using the cDNA clone resources of TAIR. In addition to filling all gaps in the subcellular map of the established chloroplast thioredoxins f, m, x and y, we show that the members of the WCRKC family are targeted to the stroma and provide evidence for a stromal location of the lilium proteins. The combined data from this and related studies indicate a consistent stromal location of the known Arabidopsis chloroplast thioredoxins except for thylakoid-bound HCF164.
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| 2. |
- Goulas, Estelle, et al.
(författare)
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The chloroplast lumen and stromal proteomes of Arabidopsis thaliana show differential sensitivity to short- and long-term exposure to low temperature.
- 2006
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Ingår i: Plant Journal. - 0960-7412 .- 1365-313X. ; 47:5, s. 720-34
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Tidskriftsartikel (refereegranskat)abstract
- Cold acclimation and over-wintering by herbaceous plants are energetically expensive and are dependent on functional plastid metabolism. To understand how the stroma and the lumen proteomes adapt to low temperatures, we have taken a proteomic approach (difference gel electrophoresis) to identify proteins that changed in abundance in Arabidopsis chloroplasts during cold shock (1 day), and short- (10 days) and long-term (40 days) acclimation to 5°C. We show that cold shock (1 day) results in minimal change in the plastid proteomes, while short-term (10 days) acclimation results in major changes in the stromal but few changes in the lumen proteome. Long-term acclimation (40 days) results in modulation of the proteomes of both compartments, with new proteins appearing in the lumen and further modulations in protein abundance occurring in the stroma. We identify 43 differentially displayed proteins that participate in photosynthesis, other plastid metabolic functions, hormone biosynthesis and stress sensing and signal transduction. These findings not only provide new insights into the cold response and acclimation of Arabidopsis, but also demonstrate the importance of studying changes in protein abundance within the relevant cellular compartment.
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| 3. |
- Granlund, Irene, 1961-, et al.
(författare)
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Light induced changes in protein expression and uniform regulation of transcription in the thylakoid lumen of Arabidopsis thaliana
- 2009
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 4:5, s. e5649-
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Tidskriftsartikel (refereegranskat)abstract
- In plants oxygenic photosynthesis is performed by large protein complexes found in the thylakoid membranes of chloroplasts. The soluble thylakoid lumen space is a narrow and compressed region within the thylakoid membrane which contains 80-200 proteins. Because the thylakoid lumen proteins are in close proximity to the protein complexes of photosynthesis, it is reasonable to assume that the lumen proteins are highly influenced by the presence of light. To identify light regulated proteins in the thylakoid lumen of Arabidopsis thaliana we developed a faster thylakoid preparation and combined this with difference gel electrophoresis (DIGE) of dark-adapted and light-adapted lumen proteomes. The DIGE experiments revealed that 19 lumen proteins exhibit increased relative protein levels after eight hour light exposure. Among the proteins showing increased abundance were the PsbP and PsbQ subunits of Photosystem II, major plastocyanin and several other proteins of known or unknown function. In addition, co-expression analysis of publicly available transcriptomic data showed that the co-regulation of lumen protein expression is not limited to light but rather that lumen protein genes exhibit a high uniformity of expression. The large proportion of thylakoid lumen proteins displaying increased abundance in light-adapted plants, taken together with the observed uniform regulation of transcription, implies that the majority of thylakoid lumen proteins have functions that are related to photosynthetic activity. This is the first time that an analysis of the differences in protein level during a normal day/night cycle has been performed and it shows that even a normal cycle of light significantly influences the thylakoid lumen proteome. In this study we also show for the first time, using co-expression analysis, that the prevalent lumenal chloroplast proteins are very similarly regulated at the level of transcription.
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| 4. |
- Hall, Michael, et al.
(författare)
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Redox control of processes in the plant chloroplast thylakoid lumen by disulphide/dithiol exchange as studied by proteomics approaches
- 2009
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Ingår i: 3rd EuPA Congress 2009 Stockholm. - Veszprem, Hungary : OOK-Press. - 9789638615640 ; , s. 629-631
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The chloroplasts of green plants are the site of oxygenic photosynthesis and important metabolic pathways including biosynthesis of carbohydrates, amino acids and lipids. Photosynthetic activity controls the activity of chloroplast enzymes using thioredoxin-mediated redox control. Recent proteome studies identified more than hundred potential thioredoxin targets indifferent chloroplast compartments and highlighted the impact of thioredoxin mediated redox control for chloroplast function. In this study, we addressed thioredoxin-linked redox control in the thylakoid lumen of Arabidopsis thaliana, and we showed that more than 40 percent of the known proteins of the lumen inside the photosynthetic thylakoid membrane reveal interactions with thioredoxin indicating a central function of thioredoxin control for the regulation of oxygenic photosynthesis.
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| 5. |
- Hall, Michael, et al.
(författare)
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Thioredoxin Interactions of the Chloroplast Lumen of Arabidopsis thaliana Indicate a Redox Regulation of the Xanthophyll Cycle
- 2008
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Ingår i: Photosynthesis. - Dordrecht : Springer. - 9781402067075 - 9781402067099 ; , s. 1099-1102
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Redox signalling via thioredoxins plays central roles in the light-mediated regulation of metabolic pathways of the chloroplast. Recent observations indicate strongly that thiotransduction pathways not only take place in the chloroplast stroma but also regulate functions of the chloroplast lumen. Thioredoxin signalling is probably an intrinsic characteristic of the entire chloroplast. Central questions are: (a) if there are thioredoxins or related proteins that can reduce luminal proteins, what are their sources of regeneration and their target proteins? (b) Are there links to other luminal pathways and how is redoxregulated luminal signal transduction coupled to the function of photosynthesis and signalling in the chloroplast stroma? This study aims to identify luminal thioredoxin targets and their biochemical functions. The initial experimental set-up using the E. coli thioredoxin/thioredoxin reductase system and fluorescence electrophoresis was able to confirm the known prevalent luminal thioredoxin targets that include PsbO1, PsbO2, TL17 and FKBP13. In addition, a novel thioredoxin interaction was observed for the enzyme violaxanthin deeopoxidase implying a role of luminal thioredoxin signals for regulation of the xanthophyll cycle.
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| 6. |
- Ingelsson, Björn, et al.
(författare)
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PeptidylProlyl Isomerase Activity in Chloroplast Thylakoid Lumen is a Dispensable Function of Immunophilins in Arabidopsis thaliana
- 2009
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Ingår i: Plant and Cell Physiology. - : Oxford University Press (OUP). - 0032-0781 .- 1471-9053. ; 50:10, s. 1801-1814
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Tidskriftsartikel (refereegranskat)abstract
- Chloroplast thylakoid lumen of Arabidopsis thaliana contains 16 immunophilins, five cyclophilins and 11 FK506-binding proteins (FKBPs), which are considered protein folding catalysts, although only two of them, AtFKBP13 and AtCYP20-2, possess peptidylprolyl cis/trans isomerase (PPIase) activity. To address the question of the physiological significance of this activity, we obtained and characterized Arabidopsis mutants deficient in the most active PPIase, AtFKBP13, and a double mutant deficient in both AtFKBP13 and AtCYP20-2. Two-dimensional gel electrophoresis of isolated thylakoid lumen, as well as immunoblotting analyses of major photosynthetic membrane protein complexes did not reveal differences in protein composition between the mutants and the wild type. No changes in the relative content of photosynthetic proteins were found by differential stable isotope labeling and liquid chromatographymass spectrometry (LC-MS) analyses. PPIase activity was measured in vitro in isolated thylakoid lumen samples using two different synthetic peptide substrates. Depending on the peptide substrate used for the assay, the PPIase activity in the thylakoid lumen of the mutants lacking either AtFKBP13 or both AtFKBP13 and AtCYP20-2 was as low as 10 or 2 of that in the wild type. Residual PPIase activity detected in the double mutant originated from AtCYP20-3, a cyclophilin from chloroplast stroma contaminating thylakoid lumen preparations. None of the mutants differed from the wild-type plants when grown under normal, cold stress or high light conditions. It is concluded that cellular functions of immunophilins in the thylakoid lumen of chloroplasts are not related to their PPIase capacity and should be investigated beyond this enzymatic activity.
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| 7. |
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| 8. |
- Kufryk, Galyna, et al.
(författare)
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Association of small CAB-like proteins (SCPs) of Synechocystis sp. PCC 6803 with Photosystem II
- 2008
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Ingår i: Photosynthesis Research. - : SpringerLink. - 0166-8595 .- 1573-5079. ; 95:2/3, s. 135-145
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Tidskriftsartikel (refereegranskat)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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| 9. |
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| 10. |
- Lindahl, Marika, et al.
(författare)
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Disulphide proteomes and interactions with thioredoxin on the track towards understanding redox regulation in chloroplasts and cyanobacteria
- 2009
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Ingår i: Journal of Proteomics. - : Elsevier. - 1874-3919 .- 1876-7737. ; 72:3, s. 416-438
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Forskningsöversikt (refereegranskat)abstract
- Light-dependent disulphide/dithiol exchange catalysed by thioredoxin is a classical example of redox regulation of chloroplast enzymes. Recent proteome studies have mapped thioredoxin target proteins in all chloroplast compartments ranging from the envelope to the thylakoid lumen. Progress in the methodologies has made it possible to identify which cysteine residues interact with thioredoxin and to tackle membrane-bound thioredoxin targets. To date, more than hundred targets of thioredoxin and glutaredoxin have been found in plastids from Arabidopsis, spinach, poplar and Chlamydomonas reinhardtii. Thioredoxin-mediated redox control appears to be a feature of the central pathways for assimilation and storage of carbon, sulphur and nitrogen, as well as for translation and protein folding. Cyanobacteria are oxygenic photosynthetic prokaryotes, which presumably share a common ancestor with higher plant plastids. As in chloroplasts, cyanobacterial thioredoxins receive electrons from the photosynthetic electron transport, and thioredoxin-targeted proteins are therefore highly interesting in the context of acclimation of these organisms to their environment. Studies of the unicellular model cyanobacterium Synechocystis sp. PCC 6803 revealed 77 thioredoxin target proteins. Notably, the functions of all these thioredoxin targets highlight essentially the same processes as those described in chloroplasts suggesting that thioredoxin-mediated redox signalling is equally significant in oxygenic photosynthetic prokaryotes and eukaryotes.
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