Sequencing of leucocidin R from Staphylococcus aureus P83 suggests that staphylococcal leucocidins and gamma-hemolysin are members of a single, two-component family of toxins.

A 2,813-bp HincII-ClaI DNA fragment encodes the two S and F components (LukS-R and LukF-R) of leucocidin R (Luk-R) which are secreted by Staphylococcus aureus P83. The two genes (lukS-R and lukF-R) belong to a single operon. Two peptidic sequences were deduced: LukS-R is a 35,721-Da polypeptide of 315 amino acids, including a signal sequence of 29 residues, and LukF-R is a 36,838-Da polypeptide of 325 amino acids, including a signal sequence of 25 residues. LukS-R and LukF-R were expressed in Escherichia coli and purified from the periplasmic space. Luk-R exerts biological activities on polymorphonuclear cells and on erythrocytes from various animals. Comparison of the amino acid sequence of LukF-R with that of the B component of gamma-hemolysin (HlgB), those of the F and S components of another recently sequenced staphylococcal leucocidin, and those of a few peptides of the F component from Panton-Valentine leucocidin suggests that all four toxins belong to a single, two-component family of toxins.