Nucleic Acids Research Advance Access published online on November 25, 2009
Nucleic Acids Research, doi:10.1093/nar/gkp1085
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Gene Regulation, Chromatin and Epigenetics |
Genome-wide gene regulation of biosynthesis and energy generation by a novel transcriptional repressor in Geobacter species
Department of Microbiology, University of Massachusetts Amherst, Morrill Science Center IV North, 639 North Pleasant Street, Amherst, MA 01003-9298, USA
*To whom correspondence should be addressed. Tel: +1 413 577 4666; Fax: +1 413 545 1578; Email: tueki{at}microbio.umass.edu
Received September 23, 2009. Revised November 5, 2009. Accepted November 5, 2009.
Geobacter species play important roles in bioremediation of contaminated environments and in electricity production from waste organic matter in microbial fuel cells. To better understand physiology of Geobacter species, expression and function of citrate synthase, a key enzyme in the TCA cycle that is important for organic acid oxidation in Geobacter species, was investigated. Geobacter sulfurreducens did not require citrate synthase for growth with hydrogen as the electron donor and fumarate as the electron acceptor. Expression of the citrate synthase gene, gltA, was repressed by a transcription factor under this growth condition. Functional and comparative genomics approaches, coupled with genetic and biochemical assays, identified a novel transcription factor termed HgtR that acts as a repressor for gltA. Further analysis revealed that HgtR is a global regulator for genes involved in biosynthesis and energy generation in Geobacter species. The hgtR gene was essential for growth with hydrogen, during which hgtR expression was induced. These findings provide important new insights into the mechanisms by which Geobacter species regulate their central metabolism under different environmental conditions.