THE GENE ENCODING THE HEAT-STABLE ENTEROTOXIN OF VIBRIO-CHOLERAE IS FLANKED BY 123-BASE PAIR DIRECT REPEATS

The heat-stable enterotoxin (01-ST) gene (sto) was cloned from chromos ome of the strain GP156 of Vibrio cholerae O1 (Inaba, El Tor) in Esche richia coli K-12, and its nucleotide seqence was determined. The nucle otide sequence of sto was very similar to that of NAG-ST gene (stn) of V. cholerae non-01. Both sto and stn were flanked by 123-base pair di rect repeats which had at least 93% homology to one another and includ ed some inverted repeats. All the strains of V. cholerae, V. mimicus, V. metschnikovii, V. hollisae and Yersinia enterocolitica examined by colony hybridization had the direct repeat sequence regardless of ST-g ene possession.