Induction of haemolytic activity inEscherichia coliby theslyAgene product

摘要

SummaryTheSalmonella typhimuriumprotein SlyAST, originally described as a cytolysin, shows sequence similarities to several known bacterial regulatory proteins. A homologue to theslyAStgene has been localised to min 37 of theEschericia coliK‐12 chromosome and has been designatedslyAECWhen introducedin transon a plasmid, theslyAECgene conferred a haemolytic phenotype on wild‐type but notclyA‐knockout strains ofE. coliK‐12. TheclyAgene encodes a novel haemolysin that is not expressed by wild‐typeE. coliunder tested laboratory conditions. Western and Northern blot analyses, and DNA‐band‐shift assays support a model whereby the SlyAECprotein activatesclyAexpression by binding to theclyApromoter region, thereby supporting the sequence similarity data in suggesting that SlyASTis a haemolysin activator rather than being a hae