Presence of glycerophospholipid:cholesterol acyltransferase and phospholipase in culture supernatant of Aeromonas hydrophila

Abstract

Human erythrocyte membrane glycerophospholipids are deacylated by A. hydrophila 13-h culture supernatants, resulting in the production of cholesterol ester, free fatty acid, and water-soluble phosphates. This activity appears to be due to the actions of an acyltransferase (phosphatide:cholesterol acyltransferase, EC 2.3.1 group) and a phospholipase (phosphatide acyl-hydrolase). The enzyme activities are produced simultaneously in late exponential/early stationary phase, are precipitated together from the culture supernatant with 85% ammonium sulfate, and are eluted together near the void volume during gel filtration on Sepharose 6B. These results suggest that A. hydrophila produces a multienzyme complex with an unusual mode of action on membrane lipids. The complex is distinct from the hemolytic factor aerolysin, which is also produced by A. hydrophila.