H-1-NMR AND H-2-NMR STUDIES OF A FRAGMENT OF PMP1, A REGULATORY SUBUNIT ASSOCIATED WITH THE YEAST PLASMA-MEMBRANE H-ATPASE - CONFORMATIONALPROPERTIES AND LIPID-PEPTIDE INTERACTIONS()

PMP1 is a 38-residue polypeptide associated with the yeast plasma memb rane H+-ATPase, found to regulate the enzyme activity. To investigate the molecular basis of the PMP1 biological function, the conformationa l properties of a synthetic PMP1 fragment, A18-F38, comprising the pre dicted C-terminal cytoplasmic domain and a part of the transmembrane a nchor have been studied by H-1- and H-2-NMR spectroscopies. High resol ution H-1-NMR experiments showed that, in deuterated DPC micelles, the A18-G34 segment adopts a well defined helix conformation. Our data su ggest that the whole PMP1 molecule forms a unique helix whose axis mig ht be slightly tilted with respect to the bilayer normal. Protonated D PC, DMPC and DMPS were incorporated in deuterated micelles containing the PMP1 fragment for studying Lipid-peptide interactions. Unusually s trong and selective intermolecular NOEs between Lipid chain and peptid e side chain protons, especially those of the unique Trp residue, were observed. Solid state H-2-NMR experiments performed on pure deuterate d POPC and mixed deuterated POPC:POPS (5:1) bilayers revealed that the PMP1 fragment specifically interacts with negatively charged PS lipid s ((C) Societe francaise de biochimie et biologie moleculaire / Elsevi er, Paris).