Nejvíce citovaný článek - PubMed ID 35463435
The growth of plants, algae, and cyanobacteria relies on the catalytic activity of the oxygen-evolving PSII complex, which uses solar energy to extract electrons from water to feed into the photosynthetic electron transport chain. PSII is proving to be an excellent system to study how large multi-subunit membrane-protein complexes are assembled in the thylakoid membrane and subsequently repaired in response to photooxidative damage. Here we summarize recent developments in understanding the biogenesis of PSII, with an emphasis on recent insights obtained from biochemical and structural analysis of cyanobacterial PSII assembly/repair intermediates. We also discuss how chlorophyll synthesis is synchronized with protein synthesis and suggest a possible role for PSI in PSII assembly. Special attention is paid to unresolved and controversial issues that could be addressed in future research.
FtsH proteases are membrane-embedded proteolytic complexes important for protein quality control and regulation of various physiological processes in bacteria, mitochondria, and chloroplasts. Like most cyanobacteria, the model species Synechocystis sp. PCC 6803 contains four FtsH homologs, FtsH1-FtsH4. FtsH1-FtsH3 form two hetero-oligomeric complexes, FtsH1/3 and FtsH2/3, which play a pivotal role in acclimation to nutrient deficiency and photosystem II quality control, respectively. FtsH4 differs from the other three homologs by the formation of a homo-oligomeric complex, and together with Arabidopsis thaliana AtFtsH7/9 orthologs, it has been assigned to another phylogenetic group of unknown function. Our results exclude the possibility that Synechocystis FtsH4 structurally or functionally substitutes for the missing or non-functional FtsH2 subunit in the FtsH2/3 complex. Instead, we demonstrate that FtsH4 is involved in the biogenesis of photosystem II by dual regulation of high light-inducible proteins (Hlips). FtsH4 positively regulates expression of Hlips shortly after high light exposure but is also responsible for Hlip removal under conditions when their elevated levels are no longer needed. We provide experimental support for Hlips as proteolytic substrates of FtsH4. Fluorescent labeling of FtsH4 enabled us to assess its localization using advanced microscopic techniques. Results show that FtsH4 complexes are concentrated in well-defined membrane regions at the inner and outer periphery of the thylakoid system. Based on the identification of proteins that co-purified with the tagged FtsH4, we speculate that FtsH4 concentrates in special compartments in which the biogenesis of photosynthetic complexes takes place.
- Klíčová slova
- FtsH4, high light-inducible protein, photosystem II biogenesis, proteolysis, thylakoid,
- MeSH
- Arabidopsis * genetika metabolismus MeSH
- chloroplasty metabolismus MeSH
- fotosystém II - proteinový komplex genetika metabolismus MeSH
- fylogeneze MeSH
- metaloproteasy genetika metabolismus MeSH
- proteasy MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- Synechocystis * genetika metabolismus MeSH
- tylakoidy metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fotosystém II - proteinový komplex MeSH
- FtsH4 protein, Arabidopsis MeSH Prohlížeč
- metaloproteasy MeSH
- proteasy MeSH
- proteiny huseníčku * MeSH
