The terminal oxidases of Paracoccus denitrificans |
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| Authors: | Jan-Willem L de Gier Mathias Lübben Willem N M Reijnders Corinne A Tipker Dirk-Jan Slotboom Rob J M van Spanning Adriaan H Stouthamer John van der Oost |
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| Institution: | Department of Molecular and Cellular Biology. BioCentrum Amsterdam, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam. The Netherlands.;European Molecular Biology Laboratory. Meyerhofstrasse 1, 69018 Heidelberg, Germany. |
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| Abstract: | Three distinct types of terminal oxidases participate in the aerobic respiratory pathways of Paracoccus denitrificans. Two alternative genes encoding sub unit I of the aa3-type cytochrome c oxidase have been isolated before, namely ctaDI and ctaDII. Each of these genes can be expressed separately to complement a double mutant (ActaDI, ActaDII), indicating that they are isoforms of subunit I of the aa3-type oxidase. The genomic locus of a quinol oxidase has been isolated: cyoABC. Thisprotohaem-containing oxidase, called cytochrome bb3, is the oniy quinoi oxidase expressed under the conditions used, in a triple oxidase mutant (ActaDI, ActaDII, cyoB::KmR) an alternative cyto-chrome c oxidase has been characterized; this cbb3-type oxidase has been partially purified. Both cytochrome aa3 and cytochrome bb3 are redox-driven proton pumps. The proton-pumping capacity of cytochrome cbb3 has been analysed; arguments for and against the active transport of protons by this novel oxidase complex are discussed. |
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