Cloning of the structural gene (hly) for the haemolysin of Vibrio cholerae El Tor strain 017.

We have cloned the DNA encoding the haemolysin of Vibrio cholerae El Tor strain 017 into the plasmid vector pBR322. The resultant plasmid, pPM431, has a 6.2-kb PstI DNA insert which leads to the production of the haemolysin in Escherichia coli K-12. Deletion analysis and transposon mutagenesis have allowed us to localize several regions affecting haemolysin production. A number of these mutants have been analysed in E. coli K-12 minicells. Three proteins have been identified: A, 80 kDal; B, 71 kDal; and C, 22 kDal. A is the haemolysin which appears to be cell-associated in E. coli K-12, and B and C are required for its efficient production. We suggest that the genes for proteins A, B and C be designated hlyA, hlyB and hlyC, respectively.