Allosteric properties of cyanobacterial cytochrome c oxidase: inhibition of the coupled enzyme by ATP and stimulation by ADP.

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 approximately 50% and 20% sequence identity to the Saccharomyces cerevisiae and beef heart mitochondrial COIV proteins, respectively.

Extended heme promiscuity in the cyanobacterial cytochrome c oxidase: characterization of native complexes containing hemes A, O, and D, respectively.

The cyanobacteria Anacystis nidulans (Synechococcus sp. PCC6301), Synechocystis sp. PCC6803, Anabaena sp.

Promiscuity of heme groups in the cyanobacterial cytochrome-C oxidase.

The cyanobacteria Nostoc sp. strain Mac, Anabaena 7937, Synechocystis 6803, and Anacystis nidulans (Synechococcus 6301) were grown and incubated in the light under three different oxygen regimes: Phase-A cells were harvested from photoautotrophically growing cultures at a cell density of 2.8-3.

Transient accumulation of heme O (cytochrome o) in the cytoplasmic membrane of semi-anaerobic Anacystis nidulans. Evidence for oxygenase-catalyzed heme O/A transformation.

Incubation of obligately photoautotrophic and aerobic cyanobacterium Anacystis nidulans (Synechococcus sp. PCC 6301) in the light in the presence of the photo-system II inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea and equilibrated with approximately 1% (v/v) O2 in N2 (10 microM O2 in solution) led to a decrease of the heme A content of isolated cytoplasmic membranes and to the appearance of heme O. The latter was not seen in membranes from fully aerated cells (> 210 microM dissolved O2).

Occurrence of heme O in photoheterotrophically growing, semi-anaerobic cyanobacterium Synechocystis sp. PCC6803.

Extraction and identification of the non-covalently bound heme groups from crude membrane preparations of photoheterotrophically grown Synechocystis sp. PCC 6803 by reversed phase high performance liquid chromatography and optical spectrophotometry led to the detection of heme O in addition to hemes B and A which latter was to be expected from the known presence of aa3-type cytochrome oxidase in cyanobacteria. In fully aerated cells (245 microM dissolved O2 in the medium) besides heme B only heme A was found while in low-oxygen cells (< 10 microM dissolved O2) heme O was present at a concentration even higher than that of heme A.

Immunological and functional localization of both F-type and P-type ATPases in cyanobacterial plasma membranes.

Plasma and thylakoid membranes were prepared and purified from cyanobacteria Anacystis nidulans (Synechococcus PCC6301), Synechocystis PCC6803, and Anabaena PCC7120 grown photoautotrophically in axenic batch cultures and harvested either during early exponential growth (< 1 microliter packed cell mass/ml medium; light-saturated cells) or during linear growth (2-3 microliters packed cell mass/ml medium; light-limited cells). ATPase activities of methanol-activated membranes were determined by measuring (a) total inorganic phosphate released from added ATP, or (b) 32P(i) released from added [gamma-32P] ATP, or (c) NADH oxidation in a coupled ATPase/pyruvate kinase/lactate dehydrogenase system. In addition, membrane proteins were immunoblotted with antibodies raised against chloroplast and mitochondrial F1 coupling factor beta subunits, and Arabidopsis plasma membrane (P-type) ATPase, respectively.