H-1-NMR AND FLUORESCENCE STUDIES OF THE COMPLEXATION OF DMPG BY WHEATNONSPECIFIC LIPID TRANSFER PROTEIN - GLOBAL FOLD OF THE COMPLEX

Plant non-specific lipid transfer proteins (LTPs) are proteins which t ransfer lipids between membranes in vitro and are believed to be invol ved in the transport of cutin monomers to the cuticle layer in vivo or in the plant defence against phytopathogens, The complexation of DMPG , a diacyl phospholipid, by wheat ns-LTP, a protein extracted from whe at seeds, was followed by (HR)-H-1 and fluorescence spectroscopy, The global fold of the protein was calculated using the DIANA software pac kage from a list of 968 distance constraints. The internal cavity volu me, a feature common to all known ns-LTP structures, was estimated to be 750 Angstrom(3) using the 'CAVITE' program, This model of the compl ex was obtained by inserting a lipid molecule in the cavity and was en ergy minimized, The study showed that the protein fold described for t he free form was only weakly affected by the insertion of the bulky li pid, Observation of some intermolecular NOEs between the protein and t he Lipid glycerol moiety revealed that the cavity entrance was located between residues His(35) and Arg(44). The resulting solution structur e was compared to the crystal structure of the maize ns-LTP/palmitate complex. (C) 1997 Federation of European Biochemical Societies.