Superoxide stress decreases expression of srfA through inhibition of transcription of the comQXP quorum-sensing locus in Bacillus subtilis.
During the course of screening for competence-deficient mutants in the mutant collection constructed by the Japan Consortium of Bacillus Functional Genomics, a disruption mutant of sodA encoding superoxide dismutase was identified as a mutant with decreased transformation efficiency. In fact, in the sodA mutant we observed a severe decrease in the expression of srfA required for the development of genetic competence. Northern and primer extension analyses revealed inhibition of the transcription of the comQXP quorum-sensing locus in the sodA mutant, thereby preventing srfA expression. Furthermore, an excess amount of superoxide anion induced by the addition of paraquat also resulted in a decrease in comQXP transcription. Thus, it was concluded that high levels of superoxide are able to inhibit specifically the transcription of the comQXP operon. In support of this conclusion, the effect of added paraquat was significantly alleviated in a comX-independent srfA expression system.
Ohsawa
Taku
T
Department of Marine Science, School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-8610, Japan.
Tsukahara
Kensuke
K
Sato
Tsutomu
T
Ogura
Mitsuo
M
D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects / Q000235:genetics; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics; D018384:Oxidative Stress; D010269:Paraquat / Q000494:pharmacology; D010453:Peptide Synthases / Q000235:genetics* / Q000378:metabolism; D053038:Quorum Sensing / Q000235:genetics; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D014166:Transferases / Q000037:antagonists & inhibitors* / Q000235:genetics
D001426:Bacterial Proteins; C087040:ComX protein, Bacillus subtilis; D008565:Membrane Proteins; D013481:Superoxides; C070739:comQ protein, Bacillus subtilis; D013482:Superoxide Dismutase; D014166:Transferases; C064995:comP protein, Bacillus subtilis; D010453:Peptide Synthases; C069542:surfactin synthetase; D010269:Paraquat