Energy conservation in the terminal region of the respiratory chain of the methylotrophic bacterium Methylophilus methylotrophus.
Reduced + CO minus reduced difference spectra of respiratory membranes prepared from methanol-limited cultures of Methylophilus methylotrophus confirm the presence of three CO-binding cytochromes i.e. cytochromes aa3, o and cco. The kinetics of cyanide inhibition indicate that the respiratory chain of this organism is branched at the level of cytochrome c to two major terminal oxidases, viz. cytochromes aa3 and o; cytochrome cco is probably not a physiologically significant oxidase. Determination of proton and charge translocation stoichiometries (leads to H+/O and leads to K+/O quotients) during oxidation of ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine shows that the terminal oxidase system of this organism exhibits a net inward translocation of 2e-, but no net proton translocation, when a pair of electrons are passed from cytochrome c to oxygen. The use of appropriate concentrations of cyanide to selectively inhibit cytochrome o indicates that the overall translocation stoichiometries are achieved by the two oxidases, aa3 and o, functioning similarly. These and other results suggest that methanol oxidase is organised as a simple redox arm with the methanol oxidation site and oxygen consumption site(s) on the periplasmic and cytoplasmic faces of the inner membrane respectively.
D002462:Cell Membrane / Q000378:metabolism; D004734:Energy Metabolism; D019605:Euryarchaeota / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010101:Oxygen Consumption / Q000187:drug effects; D011190:Potassium Cyanide / Q000494:pharmacology
D011190:Potassium Cyanide