@article {702,
	title = {Differential protein expression in the metal-reducing bacterium Geobacter sulfurreducens strain PCA grown with fumarate or ferric citrate.},
	journal = {Proteomics},
	volume = {6},
	year = {2006},
	month = {2006 Jan},
	pages = {632-40},
	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.},
	keywords = {Anaerobiosis, Bacterial Proteins, Electrophoresis, Gel, Two-Dimensional, Ferric Compounds, Fumarates, Geobacter, Oxidation-Reduction, Proteomics, Reactive Oxygen Species, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization},
	issn = {1615-9853},
	doi = {10.1002/pmic.200500137},
	author = {Khare, Tripti and Esteve-N{\'u}{\~n}ez, Abraham and Nevin, Kelly P and Zhu, Wenhong and Yates, John R and Lovley, Derek and Giometti, Carol S}
}
@article {522,
	title = {DNA microarray and proteomic analyses of the RpoS regulon in Geobacter sulfurreducens.},
	journal = {J Bacteriol},
	volume = {188},
	year = {2006},
	month = {2006 Apr},
	pages = {2792-800},
	abstract = {The regulon of the sigma factor RpoS was defined in Geobacter sulfurreducens by using a combination of DNA microarray expression profiles and proteomics. An rpoS mutant was examined under steady-state conditions with acetate as an electron donor and fumarate as an electron acceptor and with additional transcriptional profiling using Fe(III) as an electron acceptor. Expression analysis revealed that RpoS acts as both a positive and negative regulator. Many of the RpoS-dependent genes determined play roles in energy metabolism, including the tricarboxylic acid cycle, signal transduction, transport, protein synthesis and degradation, and amino acid metabolism and transport. As expected, RpoS activated genes involved in oxidative stress resistance and adaptation to nutrient limitation. Transcription of the cytochrome c oxidase operon, necessary for G. sulfurreducens growth using oxygen as an electron acceptor, and expression of at least 13 c-type cytochromes, including one previously shown to participate in Fe(III) reduction (MacA), were RpoS dependent. Analysis of a subset of the rpoS mutant proteome indicated that 15 major protein species showed reproducible differences in abundance relative to those of the wild-type strain. Protein identification using mass spectrometry indicated that the expression of seven of these proteins correlated with the microarray data. Collectively, these results indicate that RpoS exerts global effects on G. sulfurreducens physiology and that RpoS is vital to G. sulfurreducens survival under conditions typically encountered in its native subsurface environments.},
	keywords = {Adaptation, Physiological, Amino Acids, Bacterial Proteins, Biological Transport, Citric Acid Cycle, Cytochromes, Electrophoresis, Gel, Two-Dimensional, Gene Deletion, Gene Expression Regulation, Bacterial, Geobacter, Mass Spectrometry, Mutagenesis, Insertional, Oligonucleotide Array Sequence Analysis, Oxidative Stress, Protein Biosynthesis, Proteome, Regulon, Sigma Factor, Signal Transduction},
	issn = {0021-9193},
	doi = {10.1128/JB.188.8.2792-2800.2006},
	author = {N{\'u}{\~n}ez, Cinthia and Esteve-N{\'u}{\~n}ez, Abraham and Giometti, Carol and Tollaksen, Sandra and Khare, Tripti and Lin, Winston and Lovley, Derek R and Meth{\'e}, Barbara A}
}
@article {548,
	title = {Direct correlation between rates of anaerobic respiration and levels of mRNA for key respiratory genes in Geobacter sulfurreducens.},
	journal = {Appl Environ Microbiol},
	volume = {70},
	year = {2004},
	month = {2004 Sep},
	pages = {5183-9},
	abstract = {The predominance of Geobacter species in environments in which Fe(III) reduction is important has suggested that Fe(III) reduction rates might be estimated in Geobacter-dominated environments by assessing in situ activity with molecular techniques. To determine whether mRNA levels of key respiratory genes might be correlated with respiration rates in Geobacter sulfurreducens, studies were conducted with fumarate as the electron acceptor and acetate as the limiting electron donor in anaerobic continuous cultures. Levels of mRNA for a fumarate reductase gene, frdA, quantified by real-time reverse transcription-PCR were directly correlated with fumarate reduction rates. In similar studies with Fe(III) as the electron acceptor, mRNA levels for omcB, a gene for an outer membrane c-type cytochrome involved in Fe(III) reduction, were positively correlated with Fe(III) reduction rates. Levels of mRNA for frdA and omcB were also positively correlated with fumarate and Fe(III) reduction rates, respectively, when growth was limited by the availability of fumarate or Fe(III), but mRNA levels were higher than in acetate-limited cultures. Levels of mRNA for omcC, which encodes a c-type cytochrome highly similar to OmcB but not necessary for Fe(III) reduction, followed patterns different than those of omcB. This agrees with the previous finding that OmcC is not involved in Fe(III) reduction and suggests that changes in mRNA levels of omcB are related to its role in Fe(III) reduction. These results demonstrate that mRNA levels for respiratory genes might be used to estimate in situ Fe(III) reduction rates in Geobacter-dominated environments but suggest that information on environmental conditions and/or the metabolic state of Geobacter species is also required for accurate rate estimates.},
	keywords = {Anaerobiosis, Base Sequence, DNA Primers, Geobacter, Kinetics, Oxygen Consumption, Polymerase Chain Reaction, RNA, Messenger},
	issn = {0099-2240},
	doi = {10.1128/AEM.70.9.5183-5189.2004},
	author = {Chin, Kuk-Jeong and Esteve-N{\'u}{\~n}ez, Abraham and Leang, Ching and Lovley, Derek R}
}
