PilR, a transcriptional regulator for pilin and other genes required for Fe(III) reduction in Geobacter sulfurreducens.

TitlePilR, a transcriptional regulator for pilin and other genes required for Fe(III) reduction in Geobacter sulfurreducens.
Publication TypeJournal Article
Year of Publication2009
AuthorsJuárez K, Kim B-C, Nevin K, Olvera L, Reguera G, Lovley DR, Methé BA
JournalJ Mol Microbiol Biotechnol
Volume16
Issue3-4
Pagination146-58
Date Published2009
ISSN1660-2412
KeywordsBacterial Proteins, Ferric Compounds, Fimbriae Proteins, Gene Expression Regulation, Bacterial, Genes, Regulator, Geobacter, Oxidation-Reduction, Transcription, Genetic
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.

DOI10.1159/000115849
Alternate JournalJ. Mol. Microbiol. Biotechnol.
PubMed ID18253022