title: Streptomycin- and rifampin-resistant mutants of Escherichia coli perturb F exclusion of bacteriophage T7 by affecting synthesis of the F plasmid protein PifA.
abstract: Certain alleles of rpsL that confer resistance to the antibiotic streptomycin almost completely relieve F exclusion of bacteriophage T7. Introduction of a specific rpoB allele conferring resistance to rifampin into the rpsL strain restores the ability of the F-containing strain to exclude T7. This variation in the severity of F exclusion is reflected in the levels of the F-encoded inhibitor protein PifA: F'-containing cells that harbor specific rpsL alleles are phenotypically Pif-, but become Pif+ by the further acquisition of a specific rpoB allele. F-containing cells harboring the gyrA43(Ts) mutation also appear phenotypically Pif-, possibly because repression of the pif operon is enhanced by an altered DNA conformation in the gyrase mutant strain.
authors.affiliation: Department of Microbiology, University of Texas, Austin 78712-1095.
authors.forename: C K
authors.initials: CK
authors.lastname: Schmidt
authors.forename: P
authors.initials: P
authors.lastname: Kemp
authors.forename: I J
authors.initials: IJ
authors.lastname: Molineux
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D017123:Bacteriophage T7 / Q000254:growth & development*; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000821:virology*; D029968:Escherichia coli Proteins; D005144:F Factor / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins / Q000235:genetics*; D012293:Rifampin / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D011993:Recombinant Fusion Proteins; D000091243:Ribosomal Protein S9; D012269:Ribosomal Proteins; C000717190:RpsI protein, E coli; C034212:ribosomal protein S12; D001616:beta-Galactosidase; D027081:DNA Gyrase; D004250:DNA Topoisomerases, Type II; D012293:Rifampin; D013307:Streptomycin