Identification of a Salmonella typhimurium genomic region involved in invasion of HeLa and Henle-407 epithelial cells

To identify the invasion determinant, a cosmid library was constructed by c loning a genomic library of Salmonella typhimurium 82/6915 into a cosmid ve ctor, pLA2917. A genomic region involved in invasion of cultured HeLa and H enle-407 cells was subcloned into plasmid pGEM-7Z. E. coli strain DH1 carry ing pSV6235 consisting of a S. typhimurium 4.6 kb genomic region in pGEM-7Z showed invasion of cultured HeLa and Henle-407 cells. Nested sequential de letions were introduced into the 4.6 kb genomic region of pSV6235. The E. c oli recombinants which contained less than 1.5 kb deletions from the 5' end (SmaI site) of the genomic region invaded the cells as effectively as DH1 (pSV6235). The invasion of the recombinants carrying over 2.0 kb deletions from the end of pSV6235 was significantly inactivated compared to DH1 (pSV6 235). Restriction enzyme analysis showed that the 3.1 kb fragment from the 3' end of the 4.6 kb genomic region was distinguished from the Salmonella p athogenicity I genes of S. typhimurium such as the inv, spa, and hil region s showing invasion of the cultured eukaryotic cells.