Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals

White, Gaye, Shi, Zhi, Shi, Liang, Wang, Zheming, Dohnalkova, Alice C., Marshall, Matthew J., Fredrickson, James K., Zachara, John M., Butt, Julea N. ORCID: https://orcid.org/0000-0002-9624-5226, Richardson, David J. ORCID: https://orcid.org/0000-0002-6847-1832 and Clarke, Thomas A. ORCID: https://orcid.org/0000-0002-6234-1914 (2013) Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals. Proceedings of the National Academy of Sciences of the United States of America (PNAS), 110 (16). pp. 6346-6351. ISSN 1091-6490

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The mineral-respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes, MtrC and MtrA, brought together inside a transmembrane porin, MtrB, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, the established in vivo orientation, electron transfer from the interior electron carrier pool through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The rates were 10(3) times higher than those reported for reduction of goethite, hematite, and lepidocrocite by S. oneidensis, and the order of the reaction rates was consistent with those observed in S. oneidensis cultures. In contrast, established rates for single turnover reactions between purified MtrC and Fe(III) oxides were 10(3) times lower. By providing a continuous flow of electrons, the proteoliposome experiments demonstrate that conduction through MtrCAB directly to Fe(III) oxides is sufficient to support in vivo, anaerobic, solid-phase iron respiration.

Item Type: Article
Uncontrolled Keywords: cytochrome, mineral respiration, electron transfer
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Chemistry

Faculty of Science > School of Natural Sciences
Depositing User: Rachel Smith
Date Deposited: 08 May 2013 10:16
Last Modified: 21 Dec 2022 14:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/42379
DOI: 10.1073/pnas.1220074110

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