Identification of the Essential Amino Acid Residues in LukS for the Hemolytic Activity of Staphylococcal Leukocidin towards Rabbit Erythrocytes

Abstract

Staphylococcus aureus V8 (ATCC 49775) produces Panton-Valentine leukocidin (PVL) and leukocidin (Luk). PVL and Luk consist of LukF-PV and LukS-PV, and LukF and LukS, respectively. LukF and LukS cooperatively and strongly lyse rabbit erythrocytes besides human and rabbit polymorphonuclear leukocytes. LukF and LukS-PV also cooperatively lysed rabbit erythrocytes, but its activity was only 4% of that in combination [LukF-LukS] after 15 min of incubation. To identify the pivotal region responsible for the hemolytic function of LukS towards rabbit erythrocytes, we created a series of chimeric genes (lukS-PV/lukS) and mutant genes of lukS-P V and had them expressed in Escherichia coli. The chimeric and mutant proteins purified from the sonicated extract from the cells of E. coli were assayed for their hemolytic activities towards rabbit erythrocytes in combination with LukF or LukF-PV. The results indicate that a 2-residue segment (D¹²I¹³) of lukS is the minimum region essential for the hemolytic function of LukS towards rabbit erythrocytes.