An EPR spin label study of the quinol oxidase, E. coli cytochrome bo3: A search for redox induced conformational changes:A search for redox induced conformational changes

White, Gaye F., Field, Sarah, Marritt, Sophie, Oganesyan, Vasily S., Gennis, Robert B., Yap, Lai Lai, Katsonouri, Andromachi and Thomson, Andrew J. (2007) An EPR spin label study of the quinol oxidase, E. coli cytochrome bo3: A search for redox induced conformational changes:A search for redox induced conformational changes. Biochemistry, 46 (9). pp. 2355-2363. ISSN 0006-2960

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Abstract

A search for conformational changes at the cytosolic entrance to the proton channels of the heme-copper quinol oxidase (QO), cytochrome bo3, E. coli, has been carried out using site directed nitroxide spin labeling (SDSL) of cysteine residues. These were positioned at R134 and R309, on loops that link helices II and III and VI and VII at the entrances to the D and K proton channels, respectively. The motional characteristics of both labels have been determined using X- and W-band EPR spectroscopy at room temperature in selected redox levels in the reaction sequence of QO with oxygen, namely, the mixed valence carbon monoxide form (COMV), the oxidized (O) and super-oxidized (P M) states. The O to PM step is accompanied by the uptake of protons through the K pathway. We find no evidence for changes in the motional characteristics of either label that are expected to be associated with helical motions at the entrances to the channels. Because kinetic studies of mutants show that the redox gating of protons occurs deep within the D channel close to the heme-copper site, the present study implies that no motion is transmitted to the ends of the helices.

Item Type: Article
Uncontrolled Keywords: biochemistry ,/dk/atira/pure/subjectarea/asjc/1300/1303
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Chemical Sciences and Pharmacy
Faculty of Science > School of Chemistry
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Depositing User: LivePure Connector
Date Deposited: 08 Jul 2021 00:06
Last Modified: 08 Jul 2021 00:07
URI: https://ueaeprints.uea.ac.uk/id/eprint/80440
DOI: 10.1021/bi062265h

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