@article {536,
	title = {OmcF, a putative c-Type monoheme outer membrane cytochrome required for the expression of other outer membrane cytochromes in Geobacter sulfurreducens.},
	journal = {J Bacteriol},
	volume = {187},
	year = {2005},
	month = {2005 Jul},
	pages = {4505-13},
	abstract = {Outer membrane cytochromes are often proposed as likely agents for electron transfer to extracellular electron acceptors, such as Fe(III). The omcF gene in the dissimilatory Fe(III)-reducing microorganism Geobacter sulfurreducens is predicted to code for a small outer membrane monoheme c-type cytochrome. An OmcF-deficient strain was constructed, and its ability to reduce and grow on Fe(III) citrate was found to be impaired. Following a prolonged lag phase (150 h), the OmcF-deficient strain developed the ability to grow in Fe(III) citrate medium with doubling times and yields that were ca. 145\% and 70\% of those of the wild type, respectively. Comparison of the c-type cytochrome contents of outer membrane-enriched fractions prepared from wild-type and OmcF-deficient cultures confirmed the outer membrane association of OmcF and revealed multiple changes in the cytochrome content of the OmcF-deficient strain. These changes included loss of expression of two previously characterized outer membrane cytochromes, OmcB and OmcC, and overexpression of a third previously characterized outer membrane cytochrome, OmcS, during growth on Fe(III) citrate. The omcB and omcC transcripts could not be detected in the OmcF-deficient mutant by either reverse transcriptase PCR or Northern blot analyses. Expression of the omcF gene in trans restored both the capacity of the OmcF-deficient mutant to reduce Fe(III) and wild-type levels of omcB and omcC mRNA and protein. Thus, elimination of OmcF may impair Fe(III) reduction by influencing expression of OmcB, which has previously been demonstrated to play a critical role in Fe(III) reduction.},
	keywords = {Amino Acid Sequence, Bacterial Outer Membrane Proteins, Cytochromes c, Ferric Compounds, Gene Deletion, Gene Expression Regulation, Bacterial, Geobacter, Molecular Sequence Data, Oxidation-Reduction, Sequence Alignment},
	issn = {0021-9193},
	doi = {10.1128/JB.187.13.4505-4513.2005},
	author = {Kim, Byoung-Chan and Leang, Ching and Ding, Yan-Huai R and Glaven, Richard H and Coppi, Maddalena V and Lovley, Derek R}
}
@article {571,
	title = {OmcB, a c-type polyheme cytochrome, involved in Fe(III) reduction in Geobacter sulfurreducens.},
	journal = {J Bacteriol},
	volume = {185},
	year = {2003},
	month = {2003 Apr},
	pages = {2096-103},
	abstract = {Microorganisms in the family Geobacteraceae are the predominant Fe(III)-reducing microorganisms in a variety of subsurface environments in which Fe(III) reduction is an important process, but little is known about the mechanisms for electron transport to Fe(III) in these organisms. The Geobacter sulfurreducens genome was found to contain a 10-kb chromosomal duplication consisting of two tandem three-gene clusters. The last genes of the two clusters, designated omcB and omcC, encode putative outer membrane polyheme c-type cytochromes which are 79\% identical. The role of the omcB and omcC genes in Fe(III) reduction in G. sulfurreducens was investigated. OmcB and OmcC were both expressed during growth with acetate as the electron donor and either fumarate or Fe(III) as the electron acceptor. OmcB was ca. twofold more abundant under both conditions. Disrupting omcB or omcC by gene replacement had no impact on growth with fumarate. However, the OmcB-deficient mutant was greatly impaired in its ability to reduce Fe(III) both in cell suspensions and under growth conditions. In contrast, the ability of the OmcC-deficient mutant to reduce Fe(III) was similar to that of the wild type. When omcB was reintroduced into the OmcB-deficient mutant, the capacity for Fe(III) reduction was restored in proportion to the level of OmcB production. These results indicate that OmcB, but not OmcC, has a major role in electron transport to Fe(III) and suggest that electron transport to the outer membrane is an important feature in Fe(III) reduction in this organism.},
	keywords = {Amino Acid Sequence, Bacterial Outer Membrane Proteins, Bacterial Proteins, Cytochrome c Group, Deltaproteobacteria, Gene Expression Regulation, Bacterial, Iron, Molecular Sequence Data, Multigene Family, Mutation, Oxidation-Reduction, Sequence Homology, Amino Acid},
	issn = {0021-9193},
	author = {Leang, Ching and Coppi, M V and Lovley, D R}
}
