Proton Transport in the Outer‐Membrane Flavocytochrome Complex Limits the Rate of Extracellular Electron Transport. Issue 31 (29th June 2017)

• Record Type: Journal Article
• Authors: Okamoto, Akihiro; Tokunou, Yoshihide; Kalathil, Shafeer; Hashimoto, Kazuhito
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 31(2017)
• Page Start: 9082
• Page End: 9086
• Publication Date: 2017-06-29
• Subjects: ATP synthases -- cytochromes -- whole-cell electrochemistry -- kinetic isotope effect -- proton motive force; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201704241
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The microbial transfer of electrons to extracellularly located solid compounds, termed extracellular electron transport (EET), is critical for microbial electrode catalysis. Although the components of the EET pathway in the outer membrane (OM) have been identified, the role of electron/cation coupling in EET kinetics is poorly understood. We studied the dynamics of proton transport associated with EET in an OM flavocytochrome complex in Shewanella oneidensis MR‐1. Using a whole‐cell electrochemical assay, a significant kinetic isotope effect (KIE) was observed following the addition of deuterated water (D2 O). The removal of a flavin cofactor or key components of the OM flavocytochrome complex significantly increased the KIE in the presence of D2 O to values that were significantly larger than those reported for proton channels and ATP synthase, thus indicating that proton transport by OM flavocytochrome complexes limits the rate of EET. Abstract : It electrifying : Direct electron transport via an electron circuit composed of multiheme and flavin in an integral outer‐membrane (OM) flavocytochrome complex is critical for microbial electrode catalysis. Electrochemical study of the solvent kinetic isotope effect revealed that proton transport by the OM flavocytochrome limits the rate of electron transport in the iron‐reducing bacterium Shewanella oneidensis MR‐1.