CLONING AND SEQUENCE-ANALYSIS OF ANOTHER SHIGA-LIKE TOXIN IIE VARIANTGENE (SLT-IIERA) FROM AN ESCHERICHIA-COLI R107 STRAIN ISOLATED FROM RABBIT

An Escherichia coil R107 strain (O26 serotype) producing a Shiga-like toxin tie variant (SLT-IIera) was isolated from the mesenteric lymph n ode of a freshly dead rabbit carcass. The entire structural gene for t his SLT-IIera was cloned from chromosomal DNA by PCR using primers, ba sed on previously published sit-lie sequences. Nucleotide sequence ana lysis indicated that the slt-IIera gene was very similar to sit-lie (f ormerly called slt-IIv) from E. coil strains S1191 and 412; five and o ne nucleotide changes were detected in A and B subunits, respectively, which resulted in changes in amino acid sequences of the correspondin g subunits by three and one residues. Recombinant SLT-IIera and SLT-II e produced using an E. coil host-vector system showed similar cytotoxi city, suggesting that the variations in the structural gene of SLT-IIe ra have no significant effect on cytotoxic level.