IDENTIFICATION OF THE MINIMUM SEGMENT ESSENTIAL FOR THE H-GAMMA-II-SPECIFIC FUNCTION OF STAPHYLOCOCCAL GAMMA-HEMOLYSIN

Staphlococcal gamma-hemolysin consists of H gamma I (or LukF) of 34 kD a and H gamma II of 32 kDa, which cooperatively lyse human erythrocyte s. Our previous data showed that the N-terminal 57-residue segment of H gamma II is the essential region for the H gamma II function [H. Nar iya and Y. Kamio, Biosci. Biotech. Biochem., 59, 1603-1604 (1995)]. To identify the minimum amino acid residues in the 57-residue segment re sponsible for the specific hemolytic activity, a series of mutant gene s were constructed and er;pressed in Escherichia coli. The mutant prot eins were purified and assayed for their hemolytic activity, The resul ts indicate that the 5-residue segment (K(23)R(24)L(25)A(26)I(27)) of H gamma II is the minimum region essential for the H gamma II function .