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Mechanism of proton transfer through the K-C proton pathway in the Vibrio cholerae cbb(3) terminal oxidase
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics. University of Illinois at Urbana-Champaign, USA.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
Number of Authors: 42018 (English)In: Biochimica et Biophysica Acta - Bioenergetics, ISSN 0005-2728, E-ISSN 1879-2650, Vol. 1859, no 11, p. 1191-1198Article in journal (Refereed) Published
Abstract [en]

The heme-copper oxidases (HCuOs) are terminal components of the respiratory chain, catalyzing oxygen reduction coupled to the generation of a proton motive force. The C-family HCuOs, found in many pathogenic bacteria under low oxygen tension, utilize a single proton uptake pathway to deliver protons both for O-2 reduction and for proton pumping. This pathway, called the K-C-pathway, starts at Glu-49(P) in the accessory subunit CcoP, and connects into the catalytic subunit CcoN via the polar residues Tyr-(Y)-227, Asn (N)-293, Ser (S)-244, Tyr (Y)-321 and internal water molecules, and continues to the active site. However, although the residues are known to be functionally important, little is known about the mechanism and dynamics of proton transfer in the Kc-pathway. Here, we studied variants of Y227, N293 and Y321. Our results show that in the N293L variant, proton-coupled electron transfer is slowed during single-turnover oxygen reduction, and moreover it shows a pH dependence that is not observed in wildtype. This suggests that there is a shift in the plc, of an internal proton donor into an experimentally accessible range, from > 10 in wildtype to similar to 8.8 in N293L. Furthermore, we show that there are distinct roles for the conserved Y321 and Y227. In Y321F, proton uptake from bulk solution is greatly impaired, whereas Y227F shows wildtype-like rates and retains similar to 50% turnover activity. These tyrosines have evolutionary counterparts in the K-pathway of B-family HCuOs, but they do not have the same roles, indicating diversity in the proton transfer dynamics in the HCuO superfamily.

Place, publisher, year, edition, pages
2018. Vol. 1859, no 11, p. 1191-1198
Keywords [en]
Oxygen reduction, Bioenergetics, Electron transfer, Liposomes, Proton pumping
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:su:diva-162102DOI: 10.1016/j.bbabio.2018.08.002ISI: 000448092100001PubMedID: 30251700OAI: oai:DiVA.org:su-162102DiVA, id: diva2:1263675
Available from: 2018-11-16 Created: 2018-11-16 Last updated: 2018-11-16Bibliographically approved

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