The Role of Cytochromec-550 as Studied through Reverse Genetics and Mutant Characterization inSynechocystissp. PCC 6803

摘要: The gene coding for cytochrome c-550 in Synechocystis sp. PCC 6803 was cloned based on the N-terminal sequence of mature polypeptide. Using most probable translation start codon, is expected to code 160 amino acid residues. This includes a cleavable leader 25 has an Arg-Asn-Arg immediately before cleavage site; this characteristic transit peptides prokaryotes. Comparison with photosystem II-associated extrinsic 33-kDa protein from same cyanobacterium showed identity 13 out These results suggest that after synthesis apoprotein, transported into thylakoid lumen. gene, insertion and deletion mutants were constructed. In absence c-550, both capable photoautotrophic growth but at significantly reduced rate. Atrazine binding Western blot analysis these per-chlorophyll basis contained 53-67% amount II as compared wild type. II-specific oxygen-evolving activity saturating light intensity about 40% type strain. Taken together, indicate lumen contributes optimal functional stability cyanobacteria. supports our biochemical evidence associated lumenal side one proteins enhancing oxygen evolution (Shen, J.-R., Ikeuchi, M., Inoue, Y.(1992) FEBS Lett. 301, 145-149; Shen, Y.(1993) Biochemistry 32, 1825-1832). Based results, named psbV. possible evolutionary relationship among donor discussed.