Structure of a Bacterial Cell Surface Decaheme Electron Conduit

Journal Article · Mon May 23 00:00:00 EDT 2011 · Proceedings of the National Academy of Sciences of the United States of America, 108(23):9384-9389

DOI:https://doi.org/10.1073/pnas.1017200108· OSTI ID:1016439

Clarke, Thomas A; Edwards, Marcus; Gates, Andrew J; Hall, Andrea; White, Gaye; Bradley, Justin; Reardon, Catherine L; Shi, Liang; Beliaev, Alex S; Marshall, Matthew J; Wang, Zheming; Watmough, Nicholas; Fredrickson, Jim K; Zachara, John M; Butt, Julea N; Richardson, David J

Some bacterial species are able to utilize extracellular mineral forms of iron and manganese as respiratory electron acceptors. In Shewanella oneidensis this involves deca-heme cytochromes that are located on the bacterial cell surface at the termini of trans-outermembrane (OM) electron transfer conduits. The cell surface cytochromes can potentially play multiple roles in mediating electron transfer directly to insoluble electron sinks, catalyzing electron exchange with flavin electron shuttles or participating in extracellular inter-cytochrome electron exchange along ‘nanowire’ appendages. We present a 3.2 Å crystal structure of one of these deca-heme cytochromes, MtrF, that allows the spatial organization of the ten hemes to be visualized for the first time. The hemes are organized across four domains in a unique crossed conformation, in which a staggered 65 Å octa-heme chain transects the length of the protein and is bisected by a planar 45 Å tetra-heme chain that connects two extended Greek key split β-barrel domains. The structure provides molecular insight into how reduction of insoluble substrate (e.g. minerals), soluble substrates (e.g. flavins) and cytochrome redox partners might be possible in tandem at different termini of a trifurcated electron transport chain on the cell surface.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1016439
• Report Number(s): PNNL-SA-79964; 42318; KP1702030; TRN: US201112%%331
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, 108(23):9384-9389, Vol. 108, Issue 23
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
BINDING ENERGY
CRYSTAL STRUCTURE
CYTOCHROMES
ELECTRON EXCHANGE
ELECTRON TRANSFER
ELECTRONS
IRON
ISOALLOXAZINES
MANGANESE
PROTEINS
SUBSTRATES
TRANSPORT
VALENCE
Shewanella oneidensis
extracellular
cytochrome redox
deca-heme
electron exchange
nanowire
Environmental Molecular Sciences Laboratory