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Identification of a response regulator gene for catabolite control from a PCB‐degrading β‐proteobacteria, Acidovorax sp. KKS102
Author(s) -
Ohtsubo Yoshiyuki,
Goto Hiroyuki,
Nagata Yuji,
Kudo Toshiaki,
Tsuda Masataka
Publication year - 2006
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.1365-2958.2006.05197.x
Subject(s) - catabolite repression , biology , operon , activator (genetics) , repressor , lac operon , promoter , response regulator , transcription (linguistics) , gene , regulator gene , mutant , ralstonia solanacearum , microbiology and biotechnology , biochemistry , regulation of gene expression , transcription factor , plasmid , gene expression , pathogen , linguistics , philosophy
Summary Acidovorax sp. (formally Pseudomonas sp.) strain KKS102 carries a bph operon for the degradation of PCB/biphenyl. Transcription from the pE promoter for the bph operon was found to be under catabolite control, i.e. the promoter activity was at a lower level when succinate, fumarate or acetate was added to the culture. Some mutations in the immediate upstream region of the pE promoter resulted in catabolite‐insensitive and constitutively low promoter activity, suggesting that a transcriptional activator was involved in catabolite control. A genetic screen for a pE promoter activator identified two tandemly arranged genes, bphP and bphQ , that encoded proteins homologous to the sensor kinases and response regulators, respectively, of two‐component regulatory system. In the bphPQ double mutant, pE promoter activity was weak and catabolite‐insensitive, and a supply of the bphQ gene alone led to the restoration of the catabolite response. The mechanism of catabolite repression in KKS102 is explained in terms of inhibition of activation by BphQ. The genes highly similar to bphQ were found from several β‐proteobacteria, such as Burkholderia cenocepacia J2315, B. multivorans ATCC17616, B. xenovorans LB400 and Ralstonia solanacearum RS1085.