Function of thylakoid low molecular weight proteins and assembly factors in the biogenesis, activity and stability of photosynthetic complexes
Plant Physiology
Final Report Abstract
We aimed at studying the role of LMW proteins and associated factors in the assembly, stability, repair, dynamics and phosphorylation of the photosystems as well as the redox state and identity of electron carriers. Knowledge of these processes is important for the understanding of photosynthetic and acclimation processes. Using the generated mutants and knock-down lines we were able to assign molecular functions to the proteins PsbY1/PsbY2, PsbTn1/PsbTn2, TerC, PsbN and PsaI. Whereas PSII assembly was not affected in psbY1/psbY2 and psbTn1/psbTn2 double mutants, PsbY proteins are involved in determining the redox potential of Cytb559 within PSII and PsbTn proteins seem to adjust PSII activity to changing environmental conditions. PsbN was shown to be required for the formation of the heterodimeric D1/D2 reaction center early during assembly presumably leading to loss of higher order complexes in ΔpsbN mutants. Based on our work, we proposed a model in which TerC, together with ALB3, facilitates insertion of de novo synthesized thylakoid membrane proteins into the thylakoid membrane. The PSI protein PsaI is not required for the assembly but the stable association of the PsaL and PsaH proteins which form the LHCII binding pocket of PSI required for state transition. Remarkably, a rapid dark phosphorylation of LHCII in ΔpsaI and several other mutants affected in photosynthesis even after prolonged illumination with far-red light was due to an elevated nonphotochemical reduction of the PQ pool. Potential electron sources have been identified and are presently under investigation. In addition, we developed a novel semi-sterile culture technique allowing fast growth, unlimited leaf expansion and flowering of otherwise lethal tobacco mutant plants outside of the culture jar. Furthermore, this technique enables developmental studies and crossing experiments with the WT to clean the nuclear background of cultured plants. This technique could be of biotechnological interest also for the analysis of agriculturally important crop plants.
Publications
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(2019) The Low Molecular Mass Photosystem II Protein PsbTn Is Important for Light Acclimation. Plant physiology 179 (4) 1739–1753
Chen, Yang-Er; Yuan, Shu; Lezhneva, Lina; Meurer, Jörg; Schwenkert, Serena; Mamedov, Fikret; Schröder, Wolfgang P.
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(2014) Localization and topology of thylakoid membrane proteins in land plants. Bio-Protocol. 4(24):e1363
Torabi S, Plöchinger M, Meurer J
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(2014) PsbN is required for assembly of the photosystem II reaction center in Nicotiana tabacum. Plant Cell. 26(3):1183-99
Torabi S, Umate P, Manavski N, Plöchinger M, Kleinknecht L, Bogireddi H, Herrmann RG, Wanner G, Schröder WP, Meurer J
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(2014) The Arabidopsis Tellurite resistance C protein together with ALB3 is involved in photosystem II protein synthesis. Plant J. 78(2):344-56
Schneider A, Steinberger I, Strissel H, Kunz HH, Manavski N, Meurer J, Burkhard G, Jarzombski S, Schünemann D, Geimer S, Flügge UI, Leister D
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(2016) Functional Update of the Auxiliary Proteins PsbW, PsbY, HCF136, PsbN, TerC and ALB3 in Maintenance and Assembly of PSII. Front Plant Sci. 7:423
Plöchinger M, Schwenkert S, von Sydow L, Schröder WP, Meurer J
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(2016) The Low Molecular Weight Protein PsaI Stabilizes the Light-Harvesting Complex II Docking Site of Photosystem I. Plant Physiol. 172(1):450-63
Plöchinger M, Torabi S, Rantala M, Tikkanen M, Suorsa M, Jensen PE, Aro EM, Meurer J
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(2016) The PsbY protein of Arabidopsis Photosystem II is important for the redox control of cytochrome b559. Biochim Biophys Acta. 1857(9):1524-1533
von Sydow L, Schwenkert S, Meurer J, Funk C, Mamedov F, Schröder WP
