RT Journal Article SR Electronic(1) A1 Ueki, Toshiyuki. A1 Lovley, Derek R.YR 2007 T1 Heat-shock sigma factor RpoH from Geobacter sulfurreducens JF Microbiology, VO 153 IS 3 SP 838 OP 846 DO https://doi.org/10.1099/mic.0.2006/000638-0 PB Microbiology Society, SN 1465-2080, AB Recent studies with Myxococcus xanthus have suggested that homologues of the Escherichia coli heat-shock sigma factor, RpoH, may not be involved in the heat-shock response in this δ-proteobacterium. The genome of another δ-proteobacterium, Geobacter sulfurreducens, which is considered to be a representative of the Fe(III)-reducing Geobacteraceae that predominate in a diversity of subsurface environments, contains an rpoH homologue. Characterization of the G. sulfurreducens rpoH homologue revealed that it was induced by a temperature shift from 30 °C to 42 °C and that an rpoH-deficient mutant was unable to grow at 42 °C. The predicted heat-shock genes, hrcA, grpE, dnaK, groES and htpG, were heat-shock inducible in an rpoH-dependent manner, and comparison of promoter regions of these genes identified the consensus sequences for the −10 and −35 promoter elements. In addition, DNA elements identical to the CIRCE consensus sequence were found in promoters of rpoH, hrcA and groES, suggesting that these genes are regulated by a homologue of the repressor HrcA, which is known to bind the CIRCE element. These results suggest that the G. sulfurreducens RpoH homologue is the heat-shock sigma factor and that heat-shock response in G. sulfurreducens is regulated positively by RpoH as well as negatively by the HrcA/CIRCE system., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.2006/000638-0