Identification of the structural gene encoding the SH-activated hemolysin of Listeria monocytogenes: listeriolysin O is homologous to streptolysin O and pneumolysin.

By immunoblotting with an antiserum raised against purified listeriolysin O, we have detected the presence of a truncated protein of 52 kilodaltons in culture supernatants of a Tn1545-induced nonhemolytic mutant of Listeria monocytogenes (J.L. Gaillard, P. Berche, and P. Sansonetti, Infect. Immun. 52:50-55, 1986). The region of insertion of the transposon has been cloned and sequenced. The transposon had inserted in an open reading frame the listeriolysin O gene. The deduced amino acid sequence of this open reading frame revealed that listeriolysin O is homologous to streptolysin O and pneumolysin, although homologies were not detectable at the DNA level.