Characterization of an electron conduit between bacteria and the extracellular environment

Hartshorne, Robert S., Reardon, Catherine L., Ross, Daniel, Nuester, Jochen, Clarke, Thomas A., Gates, Andrew J., Mills, Paul C., Fredrickson, Jim K., Zachara, John M., Shi, Liang, Beliaev, Alex S., Marshall, Matthew J., Tien, Ming, Brantley, Susan, Butt, Julea N. and Richardson, David J. (2009) Characterization of an electron conduit between bacteria and the extracellular environment. Proceedings of the National Academy of Sciences, 106 (52). pp. 22169-22174. ISSN 0027-8424

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Abstract

A number of species of Gram-negative bacteria can use insoluble minerals of Fe(III) and Mn(IV) as extracellular respiratory electron acceptors. In some species of Shewanella, deca-heme electron transfer proteins lie at the extracellular face of the outer membrane (OM), where they can interact with insoluble substrates. To reduce extracellular substrates, these redox proteins must be charged by the inner membrane/periplasmic electron transfer system. Here, we present a spectro-potentiometric characterization of a trans-OM icosa-heme complex, MtrCAB, and demonstrate its capacity to move electrons across a lipid bilayer after incorporation into proteoliposomes. We also show that a stable MtrAB subcomplex can assemble in the absence of MtrC; an MtrBC subcomplex is not assembled in the absence of MtrA; and MtrA is only associated to the membrane in cells when MtrB is present. We propose a model for the modular organization of the MtrCAB complex in which MtrC is an extracellular element that mediates electron transfer to extracellular substrates and MtrB is a trans-OM spanning ß-barrel protein that serves as a sheath, within which MtrA and MtrC exchange electrons. We have identified the MtrAB module in a range of bacterial phyla, suggesting that it is widely used in electron exchange with the extracellular environment.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Chemistry
Depositing User: Users 2731 not found.
Date Deposited: 01 Feb 2011 13:12
Last Modified: 23 Apr 2020 23:41
URI: https://ueaeprints.uea.ac.uk/id/eprint/20554
DOI: 10.1073/PNAS.0900086106

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