Fatty acids bind to the fungal elicitor cryptogein and compete with sterols

Cryptogein is a proteinaceous elicitor of plant defense reactions which als o exhibits sterol carrier properties. In this study, we report that this pr otein binds fatty acids. The stoichiometry of the fatty acid-cryptogein com plex is 1:1. Linoleic acid and dehydroergosterol compete for the same site, but elicitin affinity is 27 times lower for fatty acid than far sterol. We show that C7 to C12 saturated and C16 to C22 unsaturated fatty acids are t he best ligands. The presence of double bonds markedly increases the affini ty of cryptogein for fatty acids. A comparison between elicitins and known lipid transfer proteins is discussed. (C) 2001 Federation of European Bioch emical Societies. Published by Elsevier Science B.V. All rights reserved.