Do cyanobacteria contain ?mammalian-type? cytochrome oxidase?

Abstract

The cytochrome content of membranes isolated from seven species of cyanobacteria was investigated in terms of conventional difference spectra, carbon monoxide difference spectra, photoaction spectra and photodissociation spectra, and by extraction of acid-labile heme followed by spectral identification. In addition, the effect of various inhibitors and activators on the oxidation of horse heart cytochrome c by the membrane was studied. Both the spectral features and the properties of the cytochrome oxidase reaction catalysed by the membranes suggested the presence of a terminal oxidase strikingly similar to mitochondrial ferrocytochrome c:oxygen oxidoreductase (EC. 1.9.3.1).

Respiratory electron transport in plasma and thylakoid membrane preparations from the cyanobacterium Anacystis nidulans

“…Table 2 shows the cyt oxidase activity together with % recoveries of this activity, and of protein, in CM and ICM frac- by 0.1 mM sulfide, 1.0 mM azide, and 20 mM salicyl aldoxime (a potent copper-chelating agent; cf. [22]), and strongly inhibited also by carbon monoxide (table 3). The reaction was sensitive to elevated ionic strength and stimulated by Tween 80.…”

Soluble CuA Domain of Cyanobacterial Cytochrome c Oxidase

“…Spectroscopic (6), inhibitor (7), and EPR studies (8), indicated that cyanobacterial respiratory chains contain an aa 3 -type cytochrome c oxidase. Finally, a gene cluster, encoding subunits II, I, and III of the aa 3 -type cytochrome c oxidase has been cloned from Synechocystis PCC 6803 (9).…”

“…The interaction with different cytochromes and plastocyanin was investigated and both cytochrome c 6 and plastocyanin were proposed as potential electron donors for the cyanobacterial CcO (22). This is interesting because cytochrome c 6 and plastocyanin have the same function in photosynthetic electron transport (Fig. 7) (23) and replace each other depending on the growth conditions (24).…”

“…The geometry of the binuclear copper center including the nature of the ligands seems to be identical to other CcOs and a tyrosine most probably serves as electron entry site. The Cu A domain is an acidic protein, as are the two in vivo electron donor candidates cytochrome c 6 and plastocyanin. The pI val- FIG.…”

Concentration and Function of Membrane-Bound Cytochromes in Cyanobacterial Heterocysts

“…The relative ratios of the different electron carriers in heterocyst and vegetative cell membranes are listed in Table I ble) in membranes from both cell types. (24) for vegetative cells from a number of cyanobacterial species.…”