title: Insertional inactivation of streptolysin S expression in Streptococcus pyogenes.
abstract: The inactivation of a genetic determinant critical for streptolysin S production was accomplished by transfer and insertion of the transposon Tn916 into the DNA of a group A streptococcal strain. The group D strain CG110 was able to efficiently transfer Tn916 into the group A strain CS91 when donor and recipient cells were concentrated and incubated together on membrane filters. Among tetracycline-resistant transconjugants, nonhemolytic mutants that no longer produced streptolysin S and retained the capacity to produce streptolysin O were discovered. Hemolytic revertants from these mutants regained tetracycline sensitivity; other revertants still retained a tetracycline resistance phenotype. Hybridization studies employing Tn916 DNA located Tn916 sequences in EcoRI and HindIII fragments of DNA from mutants devoid of streptolysin S; one carried a single copy of Tn916, and the other two carried multiple copies of the transposon.
mesh_terms: D001426:Bacterial Proteins; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D005798:Genes, Bacterial; D009154:Mutation; D013297:Streptococcus pyogenes / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D013301:Streptolysins / Q000096:biosynthesis / Q000235:genetics*; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D013301:Streptolysins; C026050:streptolysin S; D013752:Tetracycline