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HspR is a global negative regulator of heat shock gene expression in Deinococcus radiodurans
Author(s) -
Schmid Amy K.,
Howell Heather A.,
Battista John R.,
Peterson Scott N.,
Lidstrom Mary E.
Publication year - 2005
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2005.04494.x
Subject(s) - biology , promoter , deinococcus radiodurans , gene , transcription (linguistics) , gene expression , electrophoretic mobility shift assay , chaperone (clinical) , microbiology and biotechnology , regulation of gene expression , genetics , medicine , linguistics , philosophy , pathology
Summary The HspR protein functions as a negative regulator of chaperone and protease gene expression in a diversity of bacteria. Here we have identified, cloned and deleted the Deinococcus radiodurans HspR homologue, DR0934. ΔhspR mutants exhibit moderate growth defects when shifted to mild heat shock temperatures, but are severely impaired for survival at 48°C. Using quantitative reverse transcription polymerase chain reaction and global transcriptional analysis, we have identified 14 genes that are derepressed in the absence of stress in the ΔhspR background, 11 of which encode predicted chaperones and proteases, including dnaKJgrpE , ftsH , lonB , hsp20 and clpB . Promoter mapping indicated that the transcription of these genes initiates from a promoter bearing a σ 70 ‐type consensus, and that putative HspR binding sites (HAIR) were present in the 5′‐untranslated regions. Electrophoretic mobility shift assays indicated that HspR binds to these promoters at the HAIR site in vitro . These results strongly suggest that DR0934 encodes the HspR‐like global negative regulator of D. radiodurans that directly represses chaperone and protease gene expression by binding to the HAIR site in close proximity to promoter regions.