The two Staphylococcal bi‐component toxins, leukocidin and gamma‐hemolysin, share one component in common

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Abstract
Staphylococcal bi‐component toxins, leukocidin and γ‐hemolysin, consist of two protein components, i.e. F and S for leukocidin and HγI and HγII for γ‐hemolysin. In this study we purified HγI and HγII to homogeneity from the culture medium of Staphylococcus aureus RIMD 310925 and compared their properties with those of F and S purified from the same source. The N‐terminal 59‐ and C‐terminal 2‐residue amino acid sequences, apparent molecular mass, and isoelectri point of purified HγI were the same as those of F. In an Ouchterlony double diffusion test a fused line without spur was formed between F and HγI using either anti‐F or anti‐HγI antibodies. A synergistic action of F and HγII caused hemolysis of human red blood cells, and HγI acted synergistically with S to exhibit leukocidin activity. We conclude that the two toxins share one protein component (F = HγI) in common and leukocidin‐ and γ‐hemolysin‐specific activities are determined by S and HγII, respectively. It is also reported that the N‐terminal 58‐residue sequence of HγII is 72% similar to the corresponding sequence of S.