HR: 17:30h
AN: B24D-07    [Abstracts]
TI: Electrochemical Characterization Shewanella oneidensis () Mr-1 MtrABC
AU: * Nuester, J
EM: jun5@psu.edu
AF: Department of Geosciences, Penn State University, 302 Hosler Building, University Park, PA 16802, United States
AU: Ross, D E
EM: der180@psu.edu
AF: Department of Biochemistry and Molecular Biology, Penn State University, 303 Althouse Lab, University Park, PA 16802, United States
AU: Hartshorne, R S
EM: r.hartshorne@uea.ac.uk
AF: School of Biological Sciences, University of East Anglia, University of East Anglia, Norwich, N NR4 7TJ, United Kingdom
AU: Brantley, S L
EM: brantley@essc.psu.edu
AF: Earth and Environmental Systems Institute, Penn State University, 2217 EES Building, University Park, PA 16802, United States
AU: Butt, J N
EM: j.butt@uea.ac.uk
AF: School of Chemical Sciences and Pharmacy, University of East Anglia, CAP 2.52, Norwich, NR4 7TJ, United Kingdom
AU: Richardson, D
EM: d.richardson@uea.ac.uk
AF: School of Biological Sciences, University of East Anglia, University of East Anglia, Norwich, N NR4 7TJ, United Kingdom
AU: Tien, M
EM: mxt3@psu.edu
AF: Department of Biochemistry and Molecular Biology, Penn State University, 303 Althouse Lab, University Park, PA 16802, United States
AB: Dissimilatory iron-reducing bacteria have the ability to use a wide range of terminal electron acceptors including solid state iron (oxihydr)oxides. It is generally accepted that electrons are transferred by electron transfer proteins to a series of multiheme c-type cytochromes which enable the electron transport from the periplasm to the extracellular side of the outer cell membrane and across the bacteria-mineral interface to the terminal electron acceptor. In the last decade, the facultative anaerobe organism Shewanella oneidensis Mr-1 has been used as a model organism to identify, purify, and sequence single proteins involved in Fe(III) and Mn(IV) reduction, but these studies have provided little biochemical information on the actual electron transfer process within the bacterial cell. In order to extend the knowledge on electron transfer, Ross et al.(in press) have recently purified a complex from Shewanella oneidensis Mr-1 which includes the membrane proteins MtrA, MtrB, and MtrC and spans the space from the periplasm to the extracellular side of the outer membrane. In our study we applied the relatively new technique of protein film electrochemistry to the MtrABC complex to gain more biochemical information on electron transport in the membrane of Shewanella oneidensis Mr-1. A wealth of information on the reaction of redox-active sites in proteins like MtrABC can be acquired by voltammetric studies in which the protein sample is immobilized as a layer onto an electrode surface. By carrying out cyclic voltammetry over a wide range of scan rates, the data can be analyzed in terms of peak potentials versus scan rate. A simple reversible electron transfer process gives rise to a trumpet-shaped plot because the oxidation and the reduction peaks increasingly separate at high scan rate. In this contribution we show a detailed electrochemical picture of the MtrABC complex, which gives insight into the electron transfer from the periplasm to the extracellular side of the outer membrane of Shewanella oneidensis Mr-1. Such electrochemical analysis will help to understand how electrons are transferred to solid state electron acceptors such as ferrihydrite or goethite with different mineralogical and thermodynamic properties. Ross, D. E., Ruebush, S. S., Brantley, S. L., Hartshorne, R. S., Clarke, T. A., Richardson, D. J., and Tien, M., in press. Characterization of Protein/Protein Interactions Involved in Iron Reduction by Shewanella oneidensis MR-1. Applied and Environmental Microbiology.
DE: 0400 BIOGEOSCIENCES
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0463 Microbe/mineral interactions
SC: Biogeosciences [B]
MN: 2007 Fall Meeting