Mechanism Of Interaction Of Escherichia Coli σ70 With Anti-Sigma Factors

TL;DRAbstract

In bacteria, the RNA polymerase (RNAP) consists of the following subunits: α2, β, β’, ω and σ. The core RNAP (α2ββ’ω) possesses the polymerising activity and it associates with one of the sigma factors to initiate transcription from a promoter region on the DNA template. All bacteria carry an essential housekeeping sigma factor and a number of extra cytoplasmic function (ECF) sigma factors. During alternate physiological states, a major part of transcriptional regulation is carried out by sigma factors, which act as transcriptional switches, thus, making it possible for bacteria to adapt to varied environmental signals by transcribing the necessary set of genes. Bacteriophages utilise various mechanisms for subverting the bacterial biochemical machinery for their advantage. One such example in E. coli is AsiA protein encoded by an early gene of T4 bacteriophage. Because of its property of binding to σ70, AsiA can inhibit transcription from E. coli promoters bearing –10 and –35 DNA seq

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