Prevalence of Salmonella enterotoxin gene(stn) among clinical strains isolated in Korea and regulation of stn expression

摘要

Role of enterotoxin from Salmonella in pathogenesis is not known. Enterotoxin gene from Salmonella typhimurium (stn) encodes a 29 kDa toxin that has no homology to any other known enterotoxins. Expression of stn is enhanced upon contact with epithelial cell but not all strains having the stn gene express Stn. Based on PCR analysis, we found that all 36 clinical strains of Salmonella isolated in Korea tested carried the stn gene. To understand the regulation of the stn transcription, the expression of stn was studied in vitro. RNA polymerase was purified by polymin P fractionation, DNA-agarose affinity chromatography, and Mono-Q ion exchange chromatography from Salmonella. The expression of stn was inhibited by cAMP centre dot CRP complex by about 50 percent.