Extensive homology between the leukotoxin of Pasteurella haemolytica A1 and the alpha-hemolysin of Escherichia coli.

The 19.8- and 101.9-kilodalton leukotoxin proteins of Pasteurella haemolytica (LKTC and LKTA, respectively) share extensive homology with the HLYC and HLYA alpha-hemolysin proteins of Escherichia coli. The leukotoxin LKTA protein cross-reacts with hemolysin-specific antisera in Western blot (immunoblot) analysis, indicating that it shares epitopes with the alpha-hemolysin HLYA protein. Both LKTA and HLYA contain a conserved hydrophobic region, as well as a set of tandemly repeated domains. These features have been implicated in the lytic function of the alpha-hemolysin.