Regulation of the cysB gene expression in Escherichia coli

It was found by Northern-type hybridization that the amount of RNA, the transcription of which begins at the cysB regulatory gene promoter, is significantly reduced after cysB gene introduction into Escherichia coli on multicopy plasmid. This result indicates that cysB protein inhibits the transcription of its own gene. O-acetyl-L-serine, an internal inducer of E. coli and Salmonella typhimurin cysteine regulons, has no effect on cysB gene expression.