Light stress proteins from the chlorophyll a/b-binding gene family in Arabidopsis thaliana
Final Report Abstract
Plants in Nature frequently perceive environmental extremes, such light stress. To maintain their physiological functions under light stress conditions plants have developed different protection strategies that operate at morphological, anatomical and subcellular levels. The accumulation of light stress proteins from the extended light-harvesting complex (LHC) protein superfamily can be considered to be a part of such photoprotective responses in the chloroplast. Based on the predicted secondary structure, all LHC-like family members are divided into three-helix early lightinduced proteins (ELIPs), two-helix stress-enhanced proteins (SEPs) and one-helix proteins (OHPs), called also high light-induced proteins (HLIPs) in cyanobacteria and cyanophages. Two different ELIPs, six SEPs and two OHPs are encoded by the genome of Arabidopsis thaliana. In this project we investigated expression, subcellular location and physiological functions of these proteins. We demonstrated that ELIPs were not present under low light (LL) conditions and accumulated in response to high light (HL), while significant amounts of SEPs and OHPs were detected in the absence of light stress but their amounts increased during HL exposure. Furthermore, the redox status of the chloroplast regulated transcription and translation of ELIPs and some SEPs, whereby jasmonic acid, ethylene and sugars were directly or indirectly involved in the signal transduction pathway. Localization studies revealed that ELIPs and SEPs are located within the major and minor antenna of photosystem II (PSII), respectively, while OHPs form a heterodimer that accumulates in the antenna of photosystem I (PSI). Analysis of elip and sep knock out and knock down mutants showed that these proteins are not essential for photoprotection under moderate light stress conditions probably due to their functional complementation. At extreme light stress conditions elip and sep mutants showed a difference in photosynthetic performance and pigment dynamics as compared to wild type plants. In contrast, deletion of OHP1 or OHP2 in A. thaliana was lethal indicating an essential function of both proteins. Mutant plants cultivated on an external carbon source showed a photobleached phenotype, had altered chloroplast ultrastructure and were impaired in photosynthetic functions due to loss of PSI and PSII reaction center proteins. The loss of these proteins was caused by problems in their stable membrane insertion. Based on these data we propose that OHPs play a fundamental role in photosynthesis by providing photoprotection to PSI and playing a role in the assembly of photosynthetic complexes, while ELIPs and SEPs are important for photoprotection of PSII under extreme stress conditions.
Publications
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(2006). Differential expression and localization of early light-induced proteins in Arabidopsis thaliana. Plant Physiol 142, 75-87
Heddad M, Norén H, Reiser V, Dunaeva M, Andersson B and Adamska I
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(2006). Modulation of PsbS and flexible versus sustained energy dissipation by light environment in different species. Physiol Plant 127, 670-680
Demmig-Adams B, Ebbert V, Mellman DL, Mueh KE, Schaffer L, Funk C, Zarter CR, Adamska I, Jansson S and Adams III WW
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(2006). Photosynthetic capacity and light harvesting efficiency during the winter-to-spring transition in subalpine conifers. New Phytol 172, 283-292
Zarter CR, Demmig-Adams B, Ebbert V, Adamska I and Adams III WW
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(2006). Winter acclimation of PsbS and related proteins in the evergreen Arctostaphylos uva-ursi as influenced by altitude and light environment. Plant Cell Environ 29, 869- 878
Zarter CR, Adams III WW, Ebbert V, Adamska I, Jansson S and Demmig Adams B
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(2006). Winter down-regulation of intrinsic photosynthetic capacity coupled with upregulation of Elip-like proteins and persistent energy dissipation in a subalpine forest. New Phytol 172, 272-282
Zarter CR, Adams III WW, Ebbert V, Cuthbertson DJ, Adamska I and Demmig-Adams B
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(2008). Structure and dynamics of photosystem II light-harvesting complex revealed by high-resolution FTICR mass spectrometric proteome analysis. J Am Soc Mass Spectrom 19, 1004-101
Galetskiy D, Susnea I, Reiser V, Adamska I and Przybylski M
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(2010). Taxonomic distribution and origins of the extended LHC (light-harvesting complex) antenna protein superfamily. BMC Evol Biol, 10, 233
Engelken J, Brinkmann H and Adamska I
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(2011). Mass spectrometric characterization of photooxidative protein modifications in Arabidopsis thaliana thylakoid membranes. Rapid Commun Mass Spectrom 25, 184-190
Galetskiy D, Lohscheider JN, Kononikhin AS, Popov IA, Nikolaev, EN and Adamska I
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(2011). Phosphorylation and nitration levels of photosynthetic proteins are conversely regulated by light stress. Plant Mol Biol 77, 461-473
Galetskiy D, Lohscheider JN, Kononikhin AS, Popov IA, Nikolaev EN and Adamska I
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(2011). Vertical distribution of epibenthic freshwater cyanobacterial Synechococcus spp. strains depends on their ability for photoprotection. PLoS ONE, 6, e20134
Lohscheider JN, Strittmatter M, Küpper H and Adamska I
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(2012). Light stress proteins in viruses, cyanobacteria and photosynthetic eukaryota. In: Advances in Photosynthesis and Respiration, Vol. 34, Photosynthesis: Plastid Biology, Energy Conversion and Carbon Assimilation, eds J.J. Eaton-Rye, B.C. Tripathy and T.D. Sharkey, Chapter 14, pp. 299-318, Springer Science+Buisness Media B.V., Dordrecht, The Netherlands
Heddad M, Engelken J and Adamska I
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(2012). The Extended Light-Harvesting Complex (LHC) Protein Superfamily: Classification and Evolutionary Dynamics. In: Advances in Photosynthesis and Respiration, Vol. 33, Functional Genomics and Evolution of Photosynthetic Systems, eds RL Burnap and WFJ Vermaas, Chapter 11, pp. 265-284, Springer Science+Buisness Media B.V., Dordrecht, The Netherlands
Engelken J, Funk C and Adamska I
