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Proton Transport in the Outer‐Membrane Flavocytochrome Complex Limits the Rate of Extracellular Electron Transport
Author(s) -
Okamoto Akihiro,
Tokunou Yoshihide,
Kalathil Shafeer,
Hashimoto Kazuhito
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201704241
Subject(s) - shewanella oneidensis , electron transport chain , flavin group , electron transfer , chemistry , kinetic isotope effect , atp synthase , proton , chemiosmosis , deuterium , extracellular , kinetics , biophysics , photochemistry , biochemistry , bacteria , biology , enzyme , physics , atomic physics , genetics , quantum mechanics
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 (D 2 O). The removal of a flavin cofactor or key components of the OM flavocytochrome complex significantly increased the KIE in the presence of D 2 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.