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Allosteric Properties of Cyanobacterial Cytochrome c Oxidase: Inhibition of the Coupled Enzyme by ATP and Stimulation by ADP
Author(s) -
Alge Daniel,
Wastyn Marnik,
Mayer Christian,
Jungwirth Christian,
Zimmermann Ulrike,
Zoder Roland,
Fromwald Susanne,
Peschek Gunter A.
Publication year - 1999
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/713803495
Subject(s) - allosteric regulation , enzyme , cytochrome c oxidase , biochemistry , chemistry , stimulation , oxidase test , heme a , biology , neuroscience
Thorough analysis of the cta operon of Synechocystis sp. PCC6803 (grown in high‐concentration salt medium to enhance the expression of respiratory proteins) showed that, apart from ctaCDE and Fb genes potentially encoding subunits I, II, III, and a small pseudo‐bacteria‐like subunit‐IV of unknown function, a large mitochondria‐like cta‐Fm gene and a pronounced terminator structure are additional components of the operon. The deduced cta Fm gene product shows 50% and 20% sequence identity to the Saccharomyces cerevisiae and beef heart mitochondrial COIV proteins, respectively. It also shows amino acid regions (near the N terminus, on the cytosolic side) with conspicuous sequence similarities to adenylate‐binding proteins such as ATP synthase beta subunit Walker A and B consensus regions or to adenylate kinase. We suggest that, similar to the situation with beef heart mitochondria, it is the mitochondria‐like subunit‐IV of the cyanobacterial aa3‐type cytochrome‐c oxidase that confers allosteric properties to the cyanobacterial enzyme, the H+/e‐ ratios of cytochrome c oxidation being significantly lowered by ATP (intravesicular or intraliposomal) but enhanced by ADP. Therefore, the antagonistic action of ATP and ADP was in a way that the redox reaction proper, was always significantly less affected than the coupled proton translocation. Evolutionary and ecological implications of the unusualallosteric regulation ofa prokaryotic cytochrome‐c oxidase is discussed.