@article {490,
	title = {PilR, a transcriptional regulator for pilin and other genes required for Fe(III) reduction in Geobacter sulfurreducens.},
	journal = {J Mol Microbiol Biotechnol},
	volume = {16},
	year = {2009},
	month = {2009},
	pages = {146-58},
	abstract = {Growth using Fe(III) as a terminal electron acceptor is a critical physiological process in Geobacter sulfurreducens. However, the mechanisms of electron transfer during Fe(III) reduction are only now being understood. It has been demonstrated that the pili in G. sulfurreducens function as microbial nanowires conducting electrons onto Fe(III) oxides. A number of c-type cytochromes have also been shown to play important roles in Fe(III) reduction. However, the regulatory networks controlling the expression of the genes involved in such processes are not well known. Here we report that the expression of pilA, which encodes the pilistructural protein, is directly regulated by a two-component regulatory system in which PilR functions as an RpoN-dependent enhancer binding protein. Surprisingly, a deletion of the pilR gene affected not only insoluble Fe(III) reduction, which requires pili, but also soluble Fe(III) reduction, which, in contrast, does not require pili. Gene expression profiling using whole-genome DNA microarray and quantitative RT-PCR analyses obtained with a PilR-deficient mutant revealed that the expression of pilA and other pilin-related genes are downregulated, while many c-type cytochromes involved in Fe(III) reduction were differentially regulated. This is the first instance of an enhancer binding protein implicated in regulating genes involved in Fe(III) respiratory functions.},
	keywords = {Bacterial Proteins, Ferric Compounds, Fimbriae Proteins, Gene Expression Regulation, Bacterial, Genes, Regulator, Geobacter, Oxidation-Reduction, Transcription, Genetic},
	issn = {1660-2412},
	doi = {10.1159/000115849},
	author = {Ju{\'a}rez, Katy and Kim, Byoung-Chan and Nevin, Kelly and Olvera, Leticia and Reguera, Gemma and Lovley, Derek R and Meth{\'e}, Barbara A}
}
@article {480,
	title = {Insights into genes involved in electricity generation in Geobacter sulfurreducens via whole genome microarray analysis of the OmcF-deficient mutant.},
	journal = {Bioelectrochemistry},
	volume = {73},
	year = {2008},
	month = {2008 Jun},
	pages = {70-5},
	abstract = {Geobacter sulfurreducens effectively produces electricity in microbial fuel cells by oxidizing acetate with an electrode serving as the sole electron acceptor. Deletion of the gene encoding OmcF, a monoheme outer membrane c-type cytochrome, substantially decreased current production. Previous studies demonstrated that inhibition of Fe(III) reduction in the OmcF-deficient mutant could be attributed to poor transcription of the gene for OmcB, an outer membrane c-type cytochrome that is required for Fe(III) reduction. However, a mutant in which omcB was deleted produced electricity as well as wild type. Microarray analysis of the OmcF-deficient mutant versus the wild type revealed that many of the genes with the greatest decreases in transcript levels were genes whose expression was previously reported to be upregulated in cells grown with an electrode as the sole electron acceptor. These included genes with putative functions related to metal efflux and/or type I secretion and two hypothetical proteins. The outer membrane cytochromes, OmcS and OmcE, which previous studies have demonstrated are required for optimal current generation, were not detected on the outer surface of the OmcF-deficient mutant even though the omcS and omcE genes were still transcribed, suggesting that the putative secretion system could be involved in the export of outer membrane proteins necessary for electron transfer to the fuel cell anode. These results suggest that the requirement for OmcF for optimal current production is not because OmcF is directly involved in extracellular electron transfer but because OmcF is required for the appropriate transcription of other genes either directly or indirectly involved in electricity production.},
	keywords = {Bacterial Outer Membrane Proteins, Cytochromes c, Down-Regulation, Electricity, Gene Expression Regulation, Bacterial, Genome, Bacterial, Geobacter, Mutation, Oligonucleotide Array Sequence Analysis, Transcription, Genetic},
	issn = {1567-5394},
	doi = {10.1016/j.bioelechem.2008.04.023},
	author = {Kim, Byoung-Chan and Postier, Bradley L and Didonato, Raymond J and Chaudhuri, Swades K and Nevin, Kelly P and Lovley, Derek R}
}
