title: Four contiguous amino acids define the target for streptolydigin resistance in the beta subunit of Escherichia coli RNA polymerase.
abstract: Streptolydigin (stl), a bacteriostatic inhibitor of transcription elongation, interacts with the beta subunit of Escherichia coli RNA polymerase. We have defined the target for stl resistance using chemical mutagenesis and mutagenic polymerase chain reaction. Mutations resulting in stl resistance are confined to a small cluster of contiguous amino acids, amino acids 543 to 546. These stlr mutants differ from one another in their levels of resistance to stl in vivo and in vitro. We have analyzed two of the mutants, A543V and F545S, for their effects on elongation and termination in vivo and in vitro. Neither affected termination at rho-dependent or rho-independent terminators. These mutants were indistinguishable from wild type in a T7 in vitro elongation assay. F545S, however, did exhibit slower elongation kinetics in a lambda tR1 pausing assay. We conclude that mutations in the stlr region can influence transcription elongation, but that these amino acids are not directly involved in catalysis.
authors.affiliation: Department of Bacteriology, University of Wisconsin, Madison 53706.
authors.forename: L M
authors.initials: LM
authors.lastname: Heisler
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: R
authors.initials: R
authors.lastname: Landick
authors.forename: C A
authors.initials: CA
authors.lastname: Gross
mesh_terms: D000595:Amino Acid Sequence; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000633:toxicity*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000302:isolation & purification / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics / Q000378:metabolism*; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005798:Genes, Bacterial; D005838:Genotype; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D015183:Restriction Mapping
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D046911:Macromolecular Substances; C100307:streptolydigin; D012321:DNA-Directed RNA Polymerases