Nucleotide sequence of a plasmid-encoded hemolysin determinant and its comparison with a corresponding chromosomal hemolysin sequence

The complete sequence of the plasmid pHly152-encoded hemolysin (hly) determinant of Escherichia coli is presented and compared with a recently sequenced chromosomal hly determinant [1]. High sequence homology between the two hly determinants is observed withìn all four structural genes, hlyC, A, B and D, but little sequence similarities are found in the 3′- and 5′-noncoding flanking regions. In addition, the noncoding region upstream of hlyC which carries the promoter for hlyC, A and B, was sequenced for several chromosomal hly determinants. The comparison of these sequences indicates three distinct classes of promoter regions which share common putative −10 and −35 boxes at roughly the same location relative to the start of hlyC.