%0 Journal Article %A Sukupolvi, Soila %A O’connor, David %A Edwards, Mary F. %T The TraT Protein is able to Normalize the Phenotype of a Plasmid-carried Permeability Mutation of Salmonella typhimurium %D 1986 %J Microbiology, %V 132 %N 8 %P 2079-2085 %@ 1465-2080 %R https://doi.org/10.1099/00221287-132-8-2079 %I Microbiology Society, %X Summary: The isolation of different classes of antibiotic-supersensitive outer membrane permeability mutants of Salmonella typhimurium has been described previously ( Sukupolvi et al., 1984 , Journal of Bacteriology 159,704-712). One of these, the SS-A mutation, sensitizes the bacteria to gentian violet and to hydrophobic antibiotics. The phenotype of the SS-A mutant was restored to normal when a cloned fragment of the F plasmid, or the R plasmid R6-5, carrying the genes traS, T and D was introduced on a multicopy plasmid. The introduction of a plasmid carrying only the tra T gene showed thatthis gene was sufficient to restore the phenotype. Only clones with functioning traT (irrespective of copy number) restored the normal antibiotic-resistant phenotype in the SS-A mutant. An incompatibility test using a donor strain which carried transposon Tn10 in the 60 MDa plasmid of S. typhimurium and a recipient in which Tn5 was placed close to the SS-A mutation indicated that the SS-A mutation was located in the 60 MDa virulence plasmid (previously called the cryptic plasmid) of S. typhimurium. The introduction of the large virulence plasmid carrying the SS-A mutant allele into wild-type S. typhimurium or Escherichia coli resulted in strains with a phenotype identical tothat of the original SS-A mutant. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-132-8-2079