title: Site-specific mutations in the D1 polypeptide affect the susceptibility of Synechocystis 6803 cells to photoinhibition.
abstract: Photoinhibition of photosystem II in the cyanobacterium Synechocystis 6803 was followed after site-specific mutagenesis of the D1 polypeptide. Mutations were created in the stromal/cytosolic loop connecting helices D and E. Two mutations E243K and CA1, a deletion of the three glutamates 242-244 and a substitution Q241H, were made in the putative cleavage area of the D1 polypeptide. A third mutation E229D was made in the PEST-like sequence. Mutants and control cells were illuminated and FV/FM was recorded. Compared to the control, the mutants were less photoinhibited. Fluorescence relaxation after a single flash was delayed in CA1. Restoration of FV/FM after photoinhibition in the mutants was totally dependent on protein synthesis while control cells were able to recover partially also when protein synthesis was inhibited. In addition, the protein synthesis-dependent recovery of CA1 was slowed down. Our results indicate a correlation between the mutated amino acids and photoinhibition of photosystem II.
authors.affiliation: Dept. of Biology, University of Turku, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Mäenpää
authors.forename: T
authors.initials: T
authors.lastname: Kallio
authors.forename: P
authors.initials: P
authors.lastname: Mulo
authors.forename: G
authors.initials: G
authors.lastname: Salih
authors.forename: E M
authors.initials: EM
authors.lastname: Aro
authors.forename: E
authors.initials: E
authors.lastname: Tyystjärvi
authors.forename: C
authors.initials: C
authors.lastname: Jansson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005971:Glutamates / Q000235:genetics; D018698:Glutamic Acid; D008027:Light; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects*; D045332:Photosystem II Protein Complex; D010940:Plant Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects; D017384:Sequence Deletion; D013050:Spectrometry, Fluorescence; D013307:Streptomycin / Q000494:pharmacology; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D005971:Glutamates; D045332:Photosystem II Protein Complex; D010940:Plant Proteins; D018698:Glutamic Acid; D013307:Streptomycin