Aberrant gene for E1 Tor hemolysin from Vibrio cholerae non-O1, N037

Vibrio cholerae non-O1 strain N037 produced a hemolysin (NO37-Hly) which was antigenically similar to E1 Tor hemolysin (E1 Tor-Hly) but different in molecular size, hemolytic activity, and glucose binding capacity. In the gene encoding NO37-Hly, a 4-bp insertion into the structural gene for E1 Tor-Hly (hlyA) was found. The insertion in a shift of codon frames generating a new stop codon in the downstream region. NO37-Hly was a truncated product of E1 Tor-Hly sharing 90% of the N terminal region. This suggested that the 10% C-terminal region of E1 Tor-Hly is needed for the maximal hemolytic activity and glucose binding capacity.