The Roles of Outer Membrane Cytochromes of Shewanella and Geobacter in Extracellular Electron Transfer

Journal Article · Sat Aug 01 04:00:00 EDT 2009 · Environmental Microbiology Reports, 1(4):220-227

DOI:https://doi.org/10.1111/j.1758-2229.2009.00035.x· OSTI ID:963832

Shi, Liang; Richardson, David; Wang, Zheming; Kerisit, Sebastien N; Rosso, Kevin M; Zachara, John M; Fredrickson, Jim K

As key components of the electron transfer (ET) pathways used for dissimilatory reduction of solid iron [Fe(III)] and manganese [Mn(IV)] (hydr)oxides, outer membrane cytochromes MtrC and OmcA of Shewanella oneidensis MR-1 and OmcE and OmcS of Geobacter sulfurreducens mediate ET reactions extracellularly. Cell surface-exposed MtrC and OmcA can transfer electrons directly to the metal oxides. S. oneidensis MR-1 cells also secrete flavins that can facilitate ET to the oxides. The secreted flavins are thought to serve either as chelators that form soluble Fe(III)/Mn(IV)-flavin complexes or as electron shuttles that ferry the electrons from cell-associated ET proteins to the metal oxides. Cell-surface localization may also permit MtrC and OmcA to transfer electrons extracellularly to either flavin-chelated Fe(III)/Mn(IV) or oxidized flavins. OmcE and OmcS are proposed to be located on the Geobacter cell surface where they are believed to function as the intermediates to relay electrons to type IV pili, which are then hypothesized to transfer electrons directly to the metal oxides. Thus, cell surface-localization positions these outer membrane cytochromes to transfer electrons to Fe(III)/Mn(IV) oxides external to the bacterial cells either directly, indirectly, or both, demonstrating a common strategy shared by Shewanella and Geobacter for extracellular reduction of the oxides.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 963832
• Report Number(s): PNNL-SA-64248; KP1504010
• Journal Information: Environmental Microbiology Reports, 1(4):220-227, Journal Name: Environmental Microbiology Reports, 1(4):220-227 Journal Issue: 4 Vol. 1
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CYTOCHROMES
ELECTRON TRANSFER
ELECTRONS
IRON
ISOALLOXAZINES
MANGANESE
MEMBRANES
OXIDES
PROTEINS