@article {3118,
	title = {Proteome of Geobacter sulfurreducens in the presence of U(VI).},
	journal = {Microbiology (Reading)},
	volume = {160},
	year = {2014},
	month = {2014 Dec},
	pages = {2607-2617},
	abstract = {<p>Geobacter species often play an important role in the in situ bioremediation of uranium-contaminated groundwater, but little is known about how these microbes avoid uranium toxicity. To evaluate this further, the proteome of Geobacter sulfurreducens exposed to 100 {\textmu}M U(VI) acetate was compared to control cells not exposed to U(VI). Of the 1363 proteins detected from these cultures, 203 proteins had higher abundance during exposure to U(VI) compared with the control cells and 148 proteins had lower abundance. U(VI)-exposed cultures expressed lower levels of proteins involved in growth, protein and amino acid biosynthesis, as well as key central metabolism enzymes as a result of the deleterious effect of U(VI) on the growth of G. sulfurreducens. In contrast, proteins involved in detoxification, such as several efflux pumps belonging to the RND (resistance-nodulation-cell division) family, and membrane protection, and other proteins, such as chaperones and proteins involved in secretion systems, were found in higher abundance in cells exposed to U(VI). Exposing G. sulfurreducens to U(VI) resulted in a higher abundance of many proteins associated with the oxidative stress response, such as superoxide dismutase and superoxide reductase. A strain in which the gene for superoxide dismutase was deleted grew more slowly than the WT strain in the presence of U(VI), but not in its absence. The results suggested that there is no specific mechanism for uranium detoxification. Rather, multiple general stress responses are induced, which presumably enable Geobacter species to tolerate high uranium concentrations.</p>},
	keywords = {Bacterial Proteins, Gene Expression Regulation, Bacterial, Geobacter, Organometallic Compounds, Proteome},
	issn = {1465-2080},
	doi = {10.1099/mic.0.081398-0},
	author = {Orellana, Roberto and Hixson, Kim K and Murphy, Sean and Mester, T{\"u}nde and Sharma, Manju L and Lipton, Mary S and Lovley, Derek R}
}
@article {445,
	title = {Purification and characterization of OmcZ, an outer-surface, octaheme c-type cytochrome essential for optimal current production by Geobacter sulfurreducens.},
	journal = {Appl Environ Microbiol},
	volume = {76},
	year = {2010},
	month = {2010 Jun},
	pages = {3999-4007},
	abstract = {Previous studies have demonstrated that Geobacter sulfurreducens requires the c-type cytochrome OmcZ, which is present in large (OmcZ(L); 50-kDa) and small (OmcZ(S); 30-kDa) forms, for optimal current production in microbial fuel cells. This protein was further characterized to aid in understanding its role in current production. Subcellular-localization studies suggested that OmcZ(S) was the predominant extracellular form of OmcZ. N- and C-terminal amino acid sequence analysis of purified OmcZ(S) and molecular weight measurements indicated that OmcZ(S) is a cleaved product of OmcZ(L) retaining all 8 hemes, including 1 heme with the unusual c-type heme-binding motif CX(14)CH. The purified OmcZ(S) was remarkably thermally stable (thermal-denaturing temperature, 94.2 degrees C). Redox titration analysis revealed that the midpoint reduction potential of OmcZ(S) is approximately -220 mV (versus the standard hydrogen electrode [SHE]) with nonequivalent heme groups that cover a large reduction potential range (-420 to -60 mV). OmcZ(S) transferred electrons in vitro to a diversity of potential extracellular electron acceptors, such as Fe(III) citrate, U(VI), Cr(VI), Au(III), Mn(IV) oxide, and the humic substance analogue anthraquinone-2,6-disulfonate, but not Fe(III) oxide. The biochemical properties and extracellular localization of OmcZ suggest that it is well suited for promoting electron transfer in current-producing biofilms of G. sulfurreducens.},
	keywords = {Binding Sites, Bioelectric Energy Sources, Cytochromes c, Electricity, Electron Transport, Geobacter, Heme, Hot Temperature, Molecular Sequence Data, Molecular Weight, Oxidation-Reduction, Protein Binding, Protein Stability, Sequence Alignment, Sequence Analysis, Protein},
	issn = {1098-5336},
	doi = {10.1128/AEM.00027-10},
	author = {Inoue, Kengo and Qian, Xinlei and Morgado, Leonor and Kim, Byoung-Chan and Mester, T{\"u}nde and Izallalen, Mounir and Salgueiro, Carlos A and Lovley, Derek R}
}
@article {477,
	title = {Proteome of Geobacter sulfurreducens grown with Fe(III) oxide or Fe(III) citrate as the electron acceptor.},
	journal = {Biochim Biophys Acta},
	volume = {1784},
	year = {2008},
	month = {2008 Dec},
	pages = {1935-41},
	abstract = {The mechanisms for Fe(III) oxide reduction in Geobacter species are of interest because Fe(III) oxides are the most abundant form of Fe(III) in many soils and sediments and Geobacter species are prevalent Fe(III)-reducing microorganisms in many of these environments. Protein abundance in G. sulfurreducens grown on poorly crystalline Fe(III) oxide or on soluble Fe(III) citrate was compared with a global accurate mass and time tag proteomic approach in order to identify proteins that might be specifically associated with Fe(III) oxide reduction. A total of 2991 proteins were detected in G. sulfurreducens grown with acetate as the electron donor and either Fe(III) oxide or soluble Fe(III) citrate as the electron acceptor, resulting in 86\% recovery of the genes predicted to encode proteins. Of the total expressed proteins 76\% were less abundant in Fe(III) oxide cultures than in Fe(III) citrate cultures, which is consistent with the overall slower rate of metabolism during growth with an insoluble electron acceptor. A total of 269 proteins were more abundant in Fe(III) oxide-grown cells than in cells grown on Fe(III) citrate. Most of these proteins were in the energy metabolism category: primarily electron transport proteins, including 13 c-type cytochromes and PilA, the structural protein for electrically conductive pili. Several of the cytochromes that were more abundant in Fe(III) oxide-grown cells were previously shown with genetic approaches to be essential for optimal Fe(III) oxide reduction. Other proteins that were more abundant during growth on Fe(III) oxide included transport and binding proteins, proteins involved in regulation and signal transduction, cell envelope proteins, and enzymes for amino acid and protein biosynthesis, among others. There were also a substantial number of proteins of unknown function that were more abundant during growth on Fe(III) oxide. These results indicate that electron transport to Fe(III) oxide requires additional and/or different proteins than electron transfer to soluble, chelated Fe(III) and suggest proteins whose functions should be further investigated in order to better understand the mechanisms of electron transfer to Fe(III) oxide in G. sulfurreducens.},
	keywords = {Bacterial Proteins, Ferric Compounds, Gene Expression Regulation, Bacterial, Geobacter, Oxidation-Reduction, Proteome},
	issn = {0006-3002},
	doi = {10.1016/j.bbapap.2008.06.011},
	author = {Ding, Yan-Huai R and Hixson, Kim K and Aklujkar, Muktak A and Lipton, Mary S and Smith, Richard D and Lovley, Derek R and Mester, T{\"u}nde}
}
@article {518,
	title = {The proteome of dissimilatory metal-reducing microorganism Geobacter sulfurreducens under various growth conditions.},
	journal = {Biochim Biophys Acta},
	volume = {1764},
	year = {2006},
	month = {2006 Jul},
	pages = {1198-206},
	abstract = {The proteome of Geobacter sulfurreducens, a model for the Geobacter species that predominate in many Fe(III)-reducing subsurface environments, was characterized with ultra high-pressure liquid chromatography and mass spectrometry using accurate mass and time (AMT) tags as well as with more traditional two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Cells were grown under six different growth conditions in order to enhance the potential that a wide range of genes would be expressed. The AMT tag approach was able to identify a much greater number of proteins than could be detected with the 2-D PAGE approach. With the AMT approach over 3,000 gene products were identified, representing about 90\% of the total predicted gene products in the genome. A high proportion of predicted proteins in most protein role categories were detected; the highest number of proteins was identified in the hypothetical protein role category. Furthermore, 91 c-type cytochromes of 111 predicted genes in the G. sulfurreducens genome were identified. Differences in the abundance of cytochromes and other proteins under different growth conditions provided information for future functional analysis of these proteins. These results demonstrate that a high percentage of the predicted proteins in the G. sulfurreducens genome are produced and that the AMT tag approach provides a rapid method for comparing differential expression of proteins under different growth conditions in this organism.},
	keywords = {Bacterial Proteins, Bacteriological Techniques, Chromatography, High Pressure Liquid, Cytochrome c Group, Electrophoresis, Gel, Two-Dimensional, Ferric Compounds, Fumarates, Geobacter, Peptide Fragments, Proteome, Spectrometry, Mass, Electrospray Ionization},
	issn = {0006-3002},
	doi = {10.1016/j.bbapap.2006.04.017},
	author = {Ding, Yan-Huai R and Hixson, Kim K and Giometti, Carol S and Stanley, Ann and Esteve-N{\'u}{\~n}ez, Abraham and Khare, Tripti and Tollaksen, Sandra L and Zhu, Wenhong and Adkins, Joshua N and Lipton, Mary S and Smith, Richard D and Mester, T{\"u}nde and Lovley, Derek R}
}
@article {517,
	title = {A putative multicopper protein secreted by an atypical type II secretion system involved in the reduction of insoluble electron acceptors in Geobacter sulfurreducens.},
	journal = {Microbiology},
	volume = {152},
	year = {2006},
	month = {2006 Aug},
	pages = {2257-64},
	abstract = {Extracellular electron transfer onto Fe(III) oxides in Geobacter sulfurreducens is considered to require proteins that must be exported to the outer surface of the cell. In order to investigate this, the putative gene for OxpG, the pseudopilin involved in a type II general secretion pathway of Gram-negative bacteria, was deleted. The mutant was unable to grow with insoluble Fe(III) oxide as the electron acceptor. Growth on soluble Fe(III) was not affected. An analysis of proteins that accumulated in the periplasm of the oxpG mutant, but not in the wild-type, led to the identification of a secreted protein, OmpB. OmpB is predicted to be a multicopper protein, with highest homology to the manganese oxidase, MofA, from Leptothrix discophora. OmpB contains a potential Fe(III)-binding site and a fibronectin type III domain, suggesting a possible role for this protein in accessing Fe(III) oxides. OmpB was localized to the membrane fraction of G. sulfurreducens and in the supernatant of growing cultures, consistent with the type II secretion system exporting OmpB. A mutant in which ompB was deleted had the same phenotype as the oxpG mutant, suggesting that the failure to export OmpB was responsible for the inability of the oxpG-deficient mutant to reduce Fe(III) oxide. This is the first report that proposes a role for a multicopper oxidase-like protein in an anaerobic organism. These results further emphasize the importance of outer-membrane proteins in Fe(III) oxide reduction and suggest that outer-membrane proteins other than c-type cytochromes are required for Fe(III) oxide reduction in Geobacter species.},
	keywords = {Bacterial Outer Membrane Proteins, Electron Transport, Ferric Compounds, Fimbriae Proteins, Geobacter, Manganese Compounds, Mutation, Oxidation-Reduction, Oxides},
	issn = {1350-0872},
	doi = {10.1099/mic.0.28864-0},
	author = {Mehta, Teena and Childers, Susan E and Glaven, Richard and Lovley, Derek R and Mester, T{\"u}nde}
}
