Specificity of Shewanella oneidensis outer membrane cytochromes
OmcA and OmcB towards iron- and manganese-oxide surfaces
EMSL Project ID
19820
Abstract
Metal-reducing bacteria have a unique ability to reduce solid-phase iron- and manganese- oxides in anaerobic environments. Unlike oxygen, Fe and Mn oxides, in a solid form, cannot diffuse across the bacterial membrane to the inner cytoplasmic membrane, which in most organisms, is the location of the enzymes responsible for electron transfer, proton translocation, and production of adenosine triphosphate. Certain Gram-negative, dissimilatory iron-reducing bacteria (for example, Shewanella oneidensis) have developed a resourceful solution to this problem by using a unique system of proteins that shuttle electrons from an energy source in the cytoplasm, across the cytoplasmic membrane, periplasmic space, and outer membrane to the bacteriums surface. Once there, specific cytochromes transfer the electrons directly to Fe or Mn in the crystal structure of metal-bearing minerals. Recent results of the Biogeochemistry Grand Challenge suggest that two cytochromes, OmcA and OmcB (also know as MtrC), act as a terminal reductase that functions to transfer electrons directly from the bacterium to the solid-phase metal oxide. We propose to use atomic force microscopy (AFM) to examine the interactions between purified samples of OmcA and OmcB and Fe and Mn oxide surfaces. We will also use AFM to examine the binding forces between OmcA and OmcB to determine the affinity of each towards the other and determine if it is reasonable that these two cytochromes bind together to form a functional terminal metal reductase on the surface (or within the outer membrane) of the bacterium.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2006-08-24
End Date
2009-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Bose, S, M. F. Hochella Jr., Y. A. Gorby, D. W. Kennedy, D. E. McCready, A. S. Madden, and B. H. Lower. 2009. "Bioreduction of hematite nanoparticles by the dissimilatory iron reducing bacterium Shewanella oneidensis MR-1." Geochimica et Cosmochimica Acta 73: 962-976.
Brian H. Lower, Liang Shi, Ruchi Yongsunthon, Timothy C. Droubay, David E. McCready, and Steven K. Lower (2007). “Specific bonds between an iron oxide surface and outer membrane cytochromes MtrC and OmcA from Shewanella oneidensis MR-1,” J. Bacteriol. 189:4944-4952.
Eggleston CM, J Voros, L Shi, BH Lower, TC Droubay, and PJ Colberg. 2008. "Binding and Direct Electrochemistry of OmcA, an Outer-Membrane Cytochrome from an Iron Reducing Bacterium, with Oxide Electrodes: A candidate Biofuel Cell System." Inorganica Chimica Acta 361(3):769-777. doi:10.1016/j.ica.2007.07.015
Lower BH, RD Lins, ZW Oestreicher, TP Straatsma, MF Hochella Jr., L Shi, and SK Lower. 2008. "In Vitro Evolution of a Peptide with a Hematite Binding Motif That May Constitute a Natural Metal-Oxide Binding Archetype ." Environmental Science & Technology 42(10):3821-3827. doi:10.1021/es702688c
Lower B. H., R. Yongsunthon, L. Shi, L. Wildling, H. J. Gruber, N. S. Wigginton, C. L. Reardon, G. E. Pinchuk, T. C. Droubay, J-F. Boily, and S. K. Lower. 2009. "Antibody Recognition Force Microscopy Shows that Outer Membrane Cytochromes OmcA and MtrC Are Expressed on the Exterior Surface of Shewanella oneidensis MR-1." Applied and Environmental Microbiology 75:2931-2935.
Nicholas S. Wigginton, Kevin M. Rosso, Brian H. Lower, Liang Shi, and Michael F. Hochella, Jr. (2007). “Scanning Tunneling Microscopy and Spectroscopy of Bacterial Outer Membrane Cytochromes,” Geochim. et Cosmochim. Acta 71:543-555.
Saumyaditya Bose, Michael F. Hochella Jr., Yuri A. Gorby, David W. Kennedy, David E. McCready, Andrew S. Madden, and Brian H. Lower (2009). Bioreduction of Hematite Nanoparticles by the Dissimilatory Iron Reducing Bacterium Shewanella oneidensis MR-1. Geochimica et Cosmochimica Acta (in press).