title: Induction of raft-like domains by a myristoylated NAP-22 peptide and its Tyr mutant.
abstract: The N-terminally myristoylated, 19-amino acid peptide, corresponding to the amino terminus of the neuronal protein NAP-22 (NAP-22 peptide) is a naturally occurring peptide that had been shown by fluorescence to cause the sequestering of a Bodipy-labeled PtdIns(4,5)P2 in a cholesterol-dependent manner. The present work, using differential scanning calorimetry (DSC), extends the observation that formation of a PtdIns(4,5)P2-rich domain is cholesterol dependent and shows that it also leads to the formation of a cholesterol-depleted domain. The PtdIns(4,5)P2 used in the present work is extracted from natural sources and does not contain any label and has the native acyl chain composition. Peptide-induced formation of a cholesterol-depleted domain is abolished when the sole aromatic amino acid, Tyr11 is replaced with a Leu. Despite this, the modified peptide can still sequester PtdIns(4,5)P2 into domains, probably because of the presence of a cluster of cationic residues in the peptide. Cholesterol and PtdIns(4,5)P2 also modulate the insertion of the peptide into the bilayer as revealed by 1H NOESY MAS/NMR. The intensity of cross peaks between the aromatic protons of the Tyr residue and the protons of the lipid indicate that in the presence of cholesterol there is a change in the nature of the interaction of the peptide with the membrane. These results have important implications for the mechanism by which NAP-22 affects actin reorganization in neurons.
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON Canada. epand@mcmaster.ca
authors.forename: Raquel F
authors.initials: RF
authors.lastname: Epand
authors.forename: Brian G
authors.initials: BG
authors.lastname: Sayer
authors.forename: Richard M
authors.initials: RM
authors.lastname: Epand
mesh_terms: D002148:Calmodulin-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D002152:Calorimetry, Differential Scanning; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D009682:Magnetic Resonance Spectroscopy; D021962:Membrane Microdomains / Q000201:enzymology / Q000378:metabolism*; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D013696:Temperature; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
chemical_list: D002148:Calmodulin-Binding Proteins; D003598:Cytoskeletal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; C066853:Basp1 protein, rat; D014443:Tyrosine