Structures of the RNA polymerase-σ54 reveal new and conserved regulatory strategies

Keeping gene transcription in check Transcription of all genes is carried out by RNA polymerase (RNAP). The enzyme is thus a pivotal regulation point for many cell and developmental processes. In bacteria, sigma factors play a vital role in transcription regulation, with σ54 being critical for transcription of many stress response genes. Yang et al. determined the x-ray crystal structure of RNAP bound to σ54, as well as promoter DNA. In the initial inhibited state of the RNAP-σ54 complex, the σ54 blocks the template DNA from entering the RNAP active site and the downstream DNA channel. Science , this issue p. 882