Structural Organization of the RNA Polymerase-Promoter Open Complex

We have used systematic site-specific protein–DNA photocrosslinking to define interactions between bacterial RNA polymerase (RNAP) and promoter DNA in the catalytically competent RNAP-promoter open complex (RPo). We have mapped more than 100 distinct crosslinks between individual segments of RNAP subunits and individual phosphates of promoter DNA. The results provide a comprehensive description of protein–DNA interactions in RPo, permit construction of a detailed model for the structure of RPo, and permit analysis of effects of a transcriptional activator on the structure of RPo.