title: Replication mutants of Staphylococcus aureus macrolide-lincosamide-streptogramin B resistance plasmid pT48.
abstract: Copy-number mutants of Staphylococcus aureus macrolide-lincosamide-streptogramin B (MLS) resistance plasmid pT48 were isolated by their resistance to the non-inducing macrolide, tylosin. One mutant plasmid, pcopD3, showed a three- to five-fold cis-dominant increase in copy number, and nucleotide sequence analysis revealed that the mutant had a single base change within the replication region. All other pT48 mutants examined had the unusual phenotype of increased plasmid multimerization and elevated copy number. These mutants were effective in trans and DNA sequencing showed that plasmids with this phenotype were deleted in one of two ways. The deletions caused similar alterations to the C-terminus of the wild-type pT48 Rep protein. The two types of mutant Rep proteins terminate with the same pentapeptide sequence: Ala-Asn-Glu-Ile-Asp. The multimerization phenotype of these mutants can be explained by defective termination of rolling-circle type replication.
authors.affiliation: Department of Biochemistry, University of Oxford, UK.
authors.forename: I
authors.initials: I
authors.lastname: Catchpole
authors.forename: K G
authors.initials: KG
authors.lastname: Dyke
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D004261:DNA Replication / Q000235:genetics*; D004352:Drug Resistance, Microbial / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D005816:Genetic Complementation Test; D055231:Lincosamides; D018942:Macrolides; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010957:Plasmids; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics; D015645:Tylosin / Q000494:pharmacology; D014769:Virginiamycin / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D055231:Lincosamides; D018942:Macrolides; D014157:Transcription Factors; D014769:Virginiamycin; D015645:Tylosin