[Antisense transcription within the hns locus of Escherichia coli]

Scanning the entire genome of E. coli by means of pattern-recognition software PlatProm spotted out more than a thousand of potential start points for antisense transcription. Taking into account possible role of antisense RNAs in the cell regulatory networks, our top-priority interest was focused on the promoter-like sites found within genes of transcription regulators. One of them (hns) encodes a major nucleoid protein affecting expression pattern of many genomic loci. Several potential start points for antisense transcription were found within its coding sequence. Gel-retardation assays, potassium permanganate and DNAse I foot-printings confirmed the ability of the intragenic promoter located approximately 280 bp downstream of ATG to bind RNA polymerase. Primer extension revealed the cDNA of the expected size while Northern blot hybridization assumes the presence of aRNA among cellular RNAs. Relative abundance of antisense RNA and hns-mRNA in vivo exhibited dependence on growth conditions thus assuming existence of regulatory pathways keeping cellular concentration of these two transcripts at the optimal level.