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Sci Rep. 2014 Jul 11;4:5628. doi: 10.1038/srep05628.

Cell-secreted flavins bound to membrane cytochromes dictate electron transfer reactions to surfaces with diverse charge and pH.

Author information

  • 11] Departments of Earth Sciences and Biological Sciences, University of Southern California, Los Angeles, CA 90089 [2] Department of Applied Chemistry, University of Tokyo, Bunkyo-ku, Tokyo, 113-8654.
  • 2Department of Applied Chemistry, University of Tokyo, Bunkyo-ku, Tokyo, 113-8654.
  • 3Biofunctional Catalyst Research Team, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan.
  • 41] Departments of Earth Sciences and Biological Sciences, University of Southern California, Los Angeles, CA 90089 [2] J. Craig Venter Institute, San Diego, CA 92121.

Abstract

The variety of solid surfaces to and from which microbes can deliver electrons by extracellular electron transport (EET) processes via outer-membrane c-type cytochromes (OM c-Cyts) expands the importance of microbial respiration in natural environments and industrial applications. Here, we demonstrate that the bifurcated EET pathway of OM c-Cyts sustains the diversity of the EET surface in Shewanella oneidensis MR-1 via specific binding with cell-secreted flavin mononucleotide (FMN) and riboflavin (RF). Microbial current production and whole-cell differential pulse voltammetry revealed that RF and FMN enhance EET as bound cofactors in a similar manner. Conversely, FMN and RF were clearly differentiated in the EET enhancement by gene-deletion of OM c-Cyts and the dependency of the electrode potential and pH. These results indicate that RF and FMN have specific binding sites in OM c-Cyts and highlight the potential roles of these flavin-cytochrome complexes in controlling the rate of electron transfer to surfaces with diverse potential and pH.

PMID:
25012073
[PubMed - in process]
PMCID:
PMC4092373
Free PMC Article
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