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Flavin Redox Bifurcation as a Mechanism for Controlling the Direction of Electron Flow during Extracellular Electron Transfer
Author(s) -
Okamoto Akihiro,
Hashimoto Kazuhito,
Nealson Kenneth H.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201407004
Subject(s) - shewanella oneidensis , flavin group , redox , electron transfer , chemistry , electron transport chain , cofactor , microbial fuel cell , photochemistry , anode , inorganic chemistry , biochemistry , bacteria , electrode , biology , genetics , enzyme
Abstract The iron‐reducing bacterium Shewanella oneidensis MR‐1 has a dual directional electronic conduit involving 40 heme redox centers in flavin‐binding outer‐membrane c ‐type cytochromes (OM c‐ Cyts). While the mechanism for electron export from the OM c ‐Cyts to an anode is well understood, how the redox centers in OM c ‐Cyts take electrons from a cathode has not been elucidated at the molecular level. Electrochemical analysis of live cells during switching from anodic to cathodic conditions showed that altering the direction of electron flow does not require gene expression or protein synthesis, but simply redox potential shift about 300 mV for a flavin cofactor interacting with the OM c ‐Cyts. That is, the redox bifurcation of the riboflavin cofactor in OM c ‐Cyts switches the direction of electron conduction in the biological conduit at the cell–electrode interface to drive bacterial metabolism as either anode or cathode catalysts.