Author/Editor		Sepčić, Kristina; Berne, Sabina; Potrich, Cristina; Turk, Tom; Maček, Peter; Menestrina, Gianfranco
Title		Interaction of ostreolysin, a cytolytic protein from the edible mushroom Pleurotus ostreatus, with lipid membranes and modulation by lysophospholipids
Type		članek
Source		Eur J Biochem
Vol. and No.		Letnik 270
Publication year		2003
Volume		str. 1199-210
Language		eng
Abstract		Ostreolysin is a 16-kDa cytolytic protein specifically expressed in primordia and fruiting bodies of the edible mushroom Pleurotus ostreatus. To understand its interaction with lipid menbranes, we compared its effects on mammalian cells, on vesicles prepared with either pure lipids or total lipid extracts, and on dispersions of lysophospholipids or fatty acids. At nanomolar concentrations, the protein lysed human, bovine and sheep erythrocytes by a colloid-osmotic mechanism, compatible with the formation of pores of 4 nm diameter, and was cytotoxic to mammalian tumor cells. A search for lipid inhibitors of hemolysis revealed a strong effect of lysophospholipids and fatty acids, occurring below their critical micellar concentration. This effect was distinct from the capacaty of ostreolysin to bind to and permeabilize lipid membranes. In fact, permeabilization of vesicles occured only when they were prepared with lipids extracted from erythrocytes, and not with lipids axtracted from P. ostreatus or pure lipid mixtures, even if lysophospholipids or fatty acids were included. Interaction with lipid vesicles, and their permeabilization, correlated with an increase in the intrinsic fluorescence and alpha-helical content of the protein, and with aggregation, which were not detected with lysophospholipids. It appears that either an unknown lipid acceptor or a specific lipid complex is required for binding, aggregation and pore formation. The inhibitory effect of lysophospholipids may reflect a regnlatory role for these camponents on the physiological action of ostreolysin and related proteins during fruiting.
Descriptors		BASIDIOMYCETES MEMBRANE LIPIDS PHOSPHOLIPIDS FATTY ACIDS HEMOLYSINS SPECTROSCOPY, FOURIER TRANSFORM INFRARED ELECTROPHORESIS, POLYACRYLAMIDE GEL