Oxygen evolution in the thylakoid-lacking cyanobacterium Gloeobacter violaceus PCC 7421.
The oxygen-evolving reactions of the thylakoid-lacking cyanobacterium Gloeobacter violaceus PCC 7421 were compared with those of Synechocystis sp. PCC 6803. Four aspects were considered: sequence conservation in three extrinsic proteins for oxygen evolution, steady-state oxygen-evolving activity, charge recombination reactions, i.e., thermoluminescence and oscillation patterns of delayed luminescence on a second time scale and delayed fluorescence on the nanosecond time scale at -196 degrees C. Even though there were significant differences between the amino acid sequences of extrinsic proteins in G. violaceus and Synechocystis sp. PCC 6803, the oxygen-evolving activities were similar. The delayed luminescence oscillation patterns and glow curves of thermoluminescence were essentially identical between the two species, and the nanosecond delayed fluorescence spectral profiles and lifetimes were also very similar. These results indicate clearly that even though the oxygen-evolving reactions are carried out in the periplasm by components with altered amino acid sequences, the essential reaction processes for water oxidation are highly conserved. In contrast, we observed significant changes on the reduction side of photosystem II. Based on these data, we discuss the oxygen-evolving activity of G. violaceus.
Koyama
Kohei
K
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
Suzuki
Hiroyuki
H
Noguchi
Takumi
T
Akimoto
Seiji
S
Tsuchiya
Tohru
T
Mimuro
Mamoru
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D000458:Cyanobacteria / Q000378:metabolism*; D003574:Cytochrome c Group / Q000737:chemistry; D049449:Luminescence; D008345:Manganese / Q000737:chemistry; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism*; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D016415:Sequence Alignment; D013050:Spectrometry, Fluorescence; D046939:Synechocystis / Q000378:metabolism
D001426:Bacterial Proteins; D003574:Cytochrome c Group; D045332:Photosystem II Protein Complex; C107126:PsbU protein, Synechocystis; D008345:Manganese; C031732:cytochrome C-550; D010100:Oxygen