Specific requirements for cytochrome c-550 and the manganese-stabilizing protein in photoautotrophic strains of Synechocystis sp. PCC 6803 with mutations in the domain Gly-351 to Thr-436 of the chlorophyll-binding protein CP47.
The requirement of cytochrome c-550 (PSII-V) in photosystem II (PSII) has been assessed in Synechocystis sp. PCC 6803 containing mutations between Gly-351 and Thr-436 of the loop E domain of the chlorophyll a-binding protein CP47. Six photoautotrophic strains were utilized to compare the effect of removal of either the manganese-stabilizing protein (PSII-O) or PSII-V on PSII activity in vivo. These were a wild-type control; two strains with amino acid deletions, Delta(R384-V392) and Delta(G429-T436); and three carrying specific amino acid substitutions, G351L/T365Q, G351L/E364Q/T365Q, and G351L/E353Q/E355Q/T365Q. The removal of PSII-O prevented the assembly of PSII in Delta(G429-T436) but not in Delta(R384-V392). Neither Delta(G429-T436) nor Delta(R384-V392) could support photoautotrophic growth in the absence of PSII-V. In chloride-limiting conditions, the photoautotrophic growth of Delta(R384-V392) was severely impaired and that of Delta(G429-T436) totally inhibited, and no strains lacking PSII-V could grow in chloride-limiting or calcium-limiting media. Substitutions at Gly-351, Glu-353, Glu-355, and Thr-365 produced phenotypes that were similar to those of the control in the presence or absence of PSII-O and PSII-V, but removal of PSII-O from G351L/E364Q/T365Q produced a significant reduction of assembled PSII centers and an enhanced sensitivity to photoinactivation while removal of PSII-V prevented photoautotrophic growth. The additional mutants E364Q:DeltaPSII-V and E364G:DeltaPSII-V demonstrated that this inhibition was a consequence of the mutation at Glu-364. These results also show that the removal of PSII-V, in vivo, produces phenotypes in the CP47 mutants examined that are either similar or more severe than those resulting from the removal of PSII-O.
Morgan
T R
TR
Department of Biochemistry, University of Otago, Dunedin, New Zealand.
Shand
J A
JA
Clarke
S M
SM
Eaton-Rye
J J
JJ
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D002118:Calcium; D002712:Chlorides; D002734:Chlorophyll / Q000737:chemistry / Q000235:genetics; D017077:Culture Media, Conditioned; D000458:Cyanobacteria / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D003574:Cytochrome c Group / Q000737:chemistry / Q000378:metabolism*; D018698:Glutamic Acid / Q000235:genetics; D005973:Glutamine / Q000235:genetics; D005998:Glycine / Q000235:genetics; D007930:Leucine / Q000235:genetics; D045342:Light-Harvesting Protein Complexes; D008345:Manganese / Q000378:metabolism*; D008667:Metalloproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics*; D010788:Photosynthesis / Q000235:genetics; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics*; D045332:Photosystem II Protein Complex; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D013912:Threonine / Q000235:genetics
D002712:Chlorides; D017077:Culture Media, Conditioned; D003574:Cytochrome c Group; D045342:Light-Harvesting Protein Complexes; D008667:Metalloproteins; D010446:Peptide Fragments; D045322:Photosynthetic Reaction Center Complex Proteins; D045332:Photosystem II Protein Complex; D011506:Proteins; C054266:photosystem II manganese-stabilizing protein; D005973:Glutamine; C070970:photosystem II, chlorophyll-binding protein, CP-47; D002734:Chlorophyll; D013912:Threonine; D018698:Glutamic Acid; D008345:Manganese; C031732:cytochrome C-550; D007930:Leucine; D002118:Calcium; D005998:Glycine