title: Differential protein expression in the metal-reducing bacterium Geobacter sulfurreducens strain PCA grown with fumarate or ferric citrate.
abstract: Geobacter sulfurreducens, generally considered to be a strict anaerobe, is a predominant microbe in subsurface environments, where it utilizes available metals as electron acceptors. To better understand the metabolic processes involved in the metal-reduction capability of this microbe, the proteins expressed by cells grown anaerobically with either fumarate or ferric citrate as electron acceptor were compared. Proteins were separated by 2-DE under denaturing or nondenaturing conditions, and proteins varying in abundance with a high level of statistical significance (p<0.0001) were identified by peptide mass analysis. Denaturing 2-DE revealed significant differences in the relative abundance of the membrane proteins OmpA and peptidoglycan-associated lipoprotein, several metabolic enzymes, and, in addition, superoxide dismutase and rubredoxin oxidoreductase. Nondenaturing 2-DE revealed elevated catalase in cells grown with ferric citrate. These results suggest that, in addition to adjustments in membrane transport and specific metabolic pathways in response to these two different electron acceptors, distinct differences exist in the oxidative environment within the cell when fumarate or soluble ferric citrate is provided as electron acceptor. Although an anaerobe, G. sulfurreducens appears to have alternate mechanisms for dealing with reactive oxygen species in response to increased intracellular soluble iron.
authors.affiliation: Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: Tripti
authors.initials: T
authors.lastname: Khare
authors.forename: Abraham
authors.initials: A
authors.lastname: Esteve-Núñez
authors.forename: Kelly P
authors.initials: KP
authors.lastname: Nevin
authors.forename: Wenhong
authors.initials: W
authors.lastname: Zhu
authors.forename: John R
authors.initials: JR
authors.lastname: Yates
authors.forename: Derek
authors.initials: D
authors.lastname: Lovley
authors.forename: Carol S
authors.initials: CS
authors.lastname: Giometti
mesh_terms: D000693:Anaerobiosis / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005290:Ferric Compounds / Q000494:pharmacology*; D005650:Fumarates / Q000494:pharmacology*; D045302:Geobacter / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D010084:Oxidation-Reduction; D040901:Proteomics; D017382:Reactive Oxygen Species; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D005290:Ferric Compounds; D005650:Fumarates; D017382:Reactive Oxygen Species; C025314:ferric citrate; C032005:fumaric acid