Originally discovered in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1 (MR-1), key components of the Mtr (i.e. metal-reducing) pathway exist in all strains of metal-reducing Shewanella characterized. The protein components identified to date for the Mtr pathway of MR-1 include four multihaem c-Cyts (c-type cytochromes), CymA, MtrA, MtrC and OmcA, and a porin-like outer membrane protein MtrB. They are strategically positioned along the width of the MR-1 cell envelope to mediate electron transfer from the quinone/quinol pool in the inner membrane to Fe(III)-containing minerals external to the bacterial cells. A survey of microbial genomes has identified homologues of the Mtr pathway in other dissimilatory Fe(III)-reducing bacteria, including Aeromonas hydrophila, Ferrimonas balearica and Rhodoferax ferrireducens, and in the Fe(II)-oxidizing bacteria Dechloromonas aromatica RCB, Gallionella capsiferriformans ES-2 and Sideroxydans lithotrophicus ES-1. The apparent widespread distribution of Mtr pathways in both Fe(III)-reducing and Fe(II)-oxidizing bacteria suggests a bidirectional electron transfer role, and emphasizes the importance of this type of extracellular electron-transfer pathway in microbial redox transformation of iron. The organizational and electron-transfer characteristics of the Mtr pathways may be shared by other pathways used by micro-organisms for exchanging electrons with their extracellular environments.
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December 2012
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Conference Article|
November 21 2012
Mtr extracellular electron-transfer pathways in Fe(III)-reducing or Fe(II)-oxidizing bacteria: a genomic perspective
Liang Shi;
Liang Shi
1
1Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, WA 99352, U.S.A.
1To whom correspondence should be addressed (emailliang.shi@pnnl.gov).
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Kevin M. Rosso;
Kevin M. Rosso
1Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, WA 99352, U.S.A.
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John M. Zachara;
John M. Zachara
1Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, WA 99352, U.S.A.
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James K. Fredrickson
James K. Fredrickson
1Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, WA 99352, U.S.A.
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Publisher: Portland Press Ltd
Received:
April 11 2012
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2012 The Authors Journal
2012
Biochem Soc Trans (2012) 40 (6): 1261–1267.
Article history
Received:
April 11 2012
Citation
Liang Shi, Kevin M. Rosso, John M. Zachara, James K. Fredrickson; Mtr extracellular electron-transfer pathways in Fe(III)-reducing or Fe(II)-oxidizing bacteria: a genomic perspective. Biochem Soc Trans 1 December 2012; 40 (6): 1261–1267. doi: https://doi.org/10.1042/BST20120098
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