CRYSTAL-STRUCTURE OF A SIGMA(70) SUBUNIT FRAGMENT FROM ESCHERICHIA-COLI RNA-POLYMERASE

The 2.6 Angstrom crystal structure of a fragment of the sigma(70) prom oter specificity subunit of E. coli RNA polymerase is described. Resid ues involved in core RNA polymerase binding lie on one face of the str ucture. On the opposite face, aligned along one helix, are exposed res idues that interact with the -10 consensus promoter element (the Pribn ow box), including four aromatic residues involved in promoter melting . The structure suggests one way in which DNA interactions may be inhi bited in the absence of RNA polymerase and provides a framework for th e interpretation of a large number of genetic and biochemical analyses .