Identification of the Minimum Segment Essential for the HγII-Specific Function of Staphylococcal γ-Hemolysin

Abstract

Staphylococcal γ-hemolysin consists of HγI (or LukF) of 34 kDa and HγII of 32 kDa, which cooperatively lyse human erythrocytes. Our previous data showed that the N-terminal 57-residue segment of HγII is the essential region for the HγII function [H. Nariya and Y. Kamio, Biosci. Biotech, Biochem., 59, 1603-1604 (1995)]. To identify the minimum amino acid residues in the 57-residue segment responsible for the specific hemolytic activity, a series of mutant genes were constructed and expressed in Escherichia coli. The mutant proteins were purified and assayed for their hemolytic activity. The results indicate that the 5-residue segment (K²³R²⁴L²⁵A²⁶I²⁷) of HγII is the minimum region essential for the HγII function.