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Electron transfer through arsenite oxidase: insights into Rieske interaction with cytochrome c

Watson, C; Niks, D; Hille, R; Vieira, M; Schoepp-Cothenet, B; Marques, A; Romão, M; ... Santini, JM; + view all (2017) Electron transfer through arsenite oxidase: insights into Rieske interaction with cytochrome c. Biochimica et Biophysica Acta (BBA) - Bioenergetics , 1858 (10) pp. 865-872. 10.1016/j.bbabio.2017.08.003. Green open access

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Abstract

Arsenic is a widely distributed environmental toxin whose presence in drinking water poses a threat to more than 140 million people worldwide. The respiratory enzyme arsenite oxidase from various bacteria catalyses the oxidation of arsenite to arsenate and is being developed as a biosensor for arsenite. The arsenite oxidase from Rhizobium sp. str. NT-26 (a member of the Alphaproteobacteria) is a heterotetramer consisting of a large catalytic subunit (AioA), which contains a molybdenum centre and a 3Fe-4S cluster, and a small subunit (AioB) containing a Rieske 2Fe-2S cluster. Stopped-flow spectroscopy and isothermal titration calorimetry (ITC) have been used to better understand electron transfer through the redox-active centres of the enzyme, which is essential for biosensor development. Results show that oxidation of arsenite at the active site is extremely fast with a rate of >4,000 s-1 and reduction of the electron acceptor is rate-limiting. An AioB-F108A mutation results in increased activity with the artificial electron acceptor DCPIP and decreased activity with cytochrome c, which in the latter as demonstrated by ITC is not due to an effect on the protein-protein interaction but instead to an effect on electron transfer. These results provide further support that the AioB F108 is important in electron transfer between the Rieske subunit and cytochrome c and its absence in the arsenite oxidases from the Betaproteobacteria may explain the inability of these enzymes to use this electron acceptor.

Type: Article
Title: Electron transfer through arsenite oxidase: insights into Rieske interaction with cytochrome c
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.bbabio.2017.08.003
Publisher version: https://doi.org/10.1016/j.bbabio.2017.08.003
Language: English
Additional information: Copyright © 2017 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).
Keywords: Arsenite oxidase, cytochrome c, rate-limiting step, stopped-flow kinetics, Rieske protein
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > Div of Biosciences > Structural and Molecular Biology
URI: https://discovery.ucl.ac.uk/id/eprint/1569145
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