Induction of haemolytic activity in Escherichia coli by the slyA gene product |
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Authors: | Jan Oscarsson Yoshimitsu Mizunoe Bernt Eric Uhlin David J. Haydon |
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Affiliation: | Department of Microbiology, UmeåUniversity, S-901 87 Umeå, Sweden. |
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Abstract: | The Salmonella typhimurium protein SlyAST, originally described as a cytolysin, shows sequence similarities to several known bacterial regulatory proteins. A homologue to the slyASt gene has been localised to min 37 of the Eschericia coli K-12 chromosome and has been designated slyAEC When introduced in trans on a plasmid, the slyAEC gene conferred a haemolytic phenotype on wild-type but not clyA-knockout strains of E. coli K-12. The clyA gene encodes a novel haemolysin that is not expressed by wild-type E. coli under tested laboratory conditions. Western and Northern blot analyses, and DNA-band-shift assays support a model whereby the SlyAEC protein activates clyA expression by binding to the clyA promoter region, thereby supporting the sequence similarity data in suggesting that SlyAST is a haemolysin activator rather than being a haemolysin per se. |
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