engleski

Uvr+-dependent induction of the aidB1 gene in Escherichia coli and Salmonella typhimurium by anaerobiosis and by acidification

Exposure of E. coli to sublethal doses of DNA-methylating agents induces the adaptive response which confers resistance to the killing and mutagenic effects of alkylating agents, by inducing the expression of ada and alkA along with at least two other genes, lakB and aidB. The aidB gene of E. coli is subject of dual regulation by ada-depentent alkylation induction and by anaerobiosis or by acetate at pH 6.5 in an ada-independent fashion. In this study we have examined the induction of aidB1 gene in E. coli and S. typhimurium (wild type, uvrA, uvrB) by anaerobiosis and by addition of sodium acetate to growth media, at acidic pH ranging 6.0 to 6.8. Induction of aidB1 gene was monitored by assaying ß-galactosidase activity in extracts obtained from strains containing plasmid with fusion of Mud1 (bla, lac) to aidB1. Our results have shown that the treatment with 50 mM sodium acetate at an extracellular pH of 6.0 caused an almost foru fold increase ß-galactosidase activity in wild type of E. coli. This induction was observed under semianaerobic condition. However aidB1 gene could not be induced by anaerobiosis and by acidification of media in nucleotide excision repair deficient strains of E. coli and S. typhimurium.

aidB-gene; ada-independent induction; NER

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