title: The beta subunit Rif-cluster I is only angstroms away from the active center of Escherichia coli RNA polymerase.
abstract: Ribonucleotide analogs bound in the initiating site of Escherichia coli RNA polymerase-promoter complex were cross-linked to the beta subunit. Using limited proteolysis and chemical degradation, the cross-link was mapped to a segment of beta between amino acids Val516 and Arg540. This region (Rif-cluster I) is known to harbor many rifampicin-resistant (RifR) mutations. The results demonstrate that Rif-culster I is part of the "5'-face" of the active center and provide structural basis for the long-known effects of RifR mutations on transcription initiation, elongation, and termination.
mesh_terms: D001665:Binding Sites; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry*; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology*; D010449:Peptide Mapping; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D012321:DNA-Directed RNA Polymerases; D012293:Rifampin