The exposed N-terminal tail of the D1 subunit is required for rapid D1 degradation during photosystem II repair in Synechocystis sp PCC 6803.
The selective replacement of photodamaged D1 protein within the multisubunit photosystem II (PSII) complex is an important photoprotective mechanism in chloroplasts and cyanobacteria. FtsH proteases are involved at an early stage of D1 degradation, but it remains unclear how the damaged D1 subunit is recognized, degraded, and replaced. To test the role of the N-terminal region of D1 in PSII biogenesis and repair, we have constructed mutants of the cyanobacterium Synechocystis sp PCC 6803 that are truncated at the exposed N terminus. Removal of 5 or 10 residues blocked D1 synthesis, as assessed in radiolabeling experiments, whereas removal of 20 residues restored the ability to assemble oxygen-evolving dimeric PSII complexes but inhibited PSII repair at the level of D1 degradation. Overall, our results identify an important physiological role for the exposed N-terminal tail of D1 at an early step in selective D1 degradation. This finding has important implications for the recognition of damaged D1 and its synchronized replacement by a newly synthesized subunit.
Komenda
Josef
J
Institute of Microbiology, Academy of Sciences, Opatovický mlýn, 37981, Trebon, Czech Republic. komenda@alga.cz
Tichy
Martin
M
Prásil
Ondrej
O
Knoppová
Jana
J
Kuviková
Stanislava
S
de Vries
Remco
R
Nixon
Peter J
PJ
D000595:Amino Acid Sequence; D052818:Autotrophic Processes / Q000187:drug effects / Q000528:radiation effects; D019281:Dimerization; D008027:Light; D008034:Lincomycin / Q000494:pharmacology; D008954:Models, Biological; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D045332:Photosystem II Protein Complex / Q000737:chemistry* / Q000378:metabolism*; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000528:radiation effects; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D046939:Synechocystis / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D020524:Thylakoids / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects
D050505:Mutant Proteins; D045332:Photosystem II Protein Complex; D021122:Protein Subunits; D008034:Lincomycin