Transcription initiation is the most regulated step in the transcription cycle and directly affects the overall level of gene expression. Bacterial RNA polymerase (RNAP) requires a σ subunit to recognize the basal conserved promoter elements and melt DNA at the transcription start site. However, various domains and structural elements of the RNAP core enzyme directly contact promoter DNA in the promoter complex, suggesting that the σ subunit is not the only determinant of the recognition of promoter DNA and stability of the promoter complex formed by the RNAP holoenzyme. The review summarizes data on the role of the structural elements of the bacterial RNAP core enzyme in promoter recognition.
- RNA polymerase
- Transcription initiation