Identification of multicomponent histidine-aspartate phosphorelay system controlling flagellar and motility gene expression in Geobacter species.

TitleIdentification of multicomponent histidine-aspartate phosphorelay system controlling flagellar and motility gene expression in Geobacter species.
Publication TypeJournal Article
Year of Publication2012
AuthorsUeki T, Leang C, Inoue K, Lovley DR
JournalJ Biol Chem
Volume287
Issue14
Pagination10958-66
Date Published2012 Mar 30
ISSN1083-351X
Abstract

Geobacter species play an important role in the natural biogeochemical cycles of aquatic sediments and subsurface environments as well as in subsurface bioremediation by oxidizing organic compounds with the reduction of insoluble Fe(III) oxides. Flagellum-based motility is considered to be critical for Geobacter species to locate fresh sources of Fe(III) oxides. Functional and comparative genomic approaches, coupled with genetic and biochemical methods, identified key regulators for flagellar gene expression in Geobacter species. A master transcriptional regulator, designated FgrM, is a member of the enhancer-binding protein family. The fgrM gene in the most studied strain of Geobacter species, Geobacter sulfurreducens strain DL-1, is truncated by a transposase gene, preventing flagellar biosynthesis. Integrating a functional FgrM homolog restored flagellar biosynthesis and motility in G. sulfurreducens DL-1 and enhanced the ability to reduce insoluble Fe(III) oxide. Interrupting the fgrM gene in G. sulfurreducens strain KN400, which is motile, removed the capacity for flagellar production and inhibited Fe(III) oxide reduction. FgrM, which is also a response regulator of the two-component His-Asp phosphorelay system, was phosphorylated by histidine kinase GHK4, which was essential for flagellar production and motility. GHK4, which is a hybrid kinase with a receiver domain at the N terminus, was phosphorylated by another histidine kinase, GHK3. Therefore, the multicomponent His-Asp phosphorelay system appears to control flagellar gene expression in Geobacter species.

DOI10.1074/jbc.M112.345041
Alternate JournalJ. Biol. Chem.
PubMed ID22362768