title: RNA polymerase binding using a strongly acidic hydrophobic-repeat region of sigma 54.
abstract: sigma 54 is a rare bacterial protein that substitutes for sigma 70 in the case of Escherichia coli genes transcribed by certain activators with enhancer protein-like properties. It contains a strongly acidic region of previously unknown function. Gel mobility-shift assays using sigma 54 deletion mutants show that this region is essential for sigma 54 to bind the core RNA polymerase and recruit it to the promoter. Multiple-point mutational analysis shows that the acidic amino acids and overlapping periodic hydrophobic amino acids are necessary for this binding. Related sequences are not found within the core binding determinant of sigma 70, which binds the same core RNA polymerase. This comparison suggests that the core RNA polymerase interacts differently with the two sigma factors, likely contributing to the critical differences in transcription mechanism in the two cases.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569.
authors.forename: Y
authors.initials: Y
authors.lastname: Tintut
authors.forename: C
authors.initials: C
authors.lastname: Wong
authors.forename: Y
authors.initials: Y
authors.lastname: Jiang
authors.forename: M
authors.initials: M
authors.lastname: Hsieh
authors.forename: J D
authors.initials: JD
authors.lastname: Gralla
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry / Q000378:metabolism*; D004586:Electrophoresis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029968:Escherichia coli Proteins; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D051877:RNA Polymerase Sigma 54; D017386:Sequence Homology, Amino Acid; D012808:Sigma Factor / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic; D014867:Water / Q000737:chemistry
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C497751:rpoN protein, E coli; D014867:Water; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54