title: Membrane interaction of disease-related dynorphin A variants.
abstract: The membrane interaction properties of two single-residue variants, R6W and L5S, of the 17-amino acid neuropeptide dynorphin A (DynA) were studied by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy. Corresponding gene mutations have recently been discovered in humans and causatively linked to a neurodegenerative disorder. The peptides were investigated in buffer and in isotropic solutions of q = 0.3 bicelles with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) or DMPC (0.8) and 1,2-dimyristoyl-sn-glycero-3-phospho(1'-rac-glycerol) (DMPG) (0.2). The CD results and the NMR secondary chemical shifts show that R6W-DynA has a small α-helical fraction in buffer, which increases in the presence of bicelles, while L5S-DynA is mainly unstructured under all conditions studied here. R6W-DynA has an almost complete association with zwitterionic bicelles (∼90%, as probed by NMR diffusion experiments), similar to the behavior of wtDynA, while L5S-DynA has a weaker association (∼50%). For all peptides, the level of bicelle association is increased in negatively charged bicelles. The L5A-DynA peptide adopts a very shallow position in the headgroup region of the bicelle bilayer, as studied by paramagnetic spin relaxation enhancement experiments using paramagnetic probes. Similarly, the results show that R6W-DynA is more deeply buried in the bilayer, with only the C-terminal residues exposed to solvent, again more similar to the case of wild-type DynA. We suggest that the results presented here may explain the differences in cell toxicity of these disease-related neuropeptide variants.
authors.affiliation: Department of Biochemistry and Biophysics, The Arrhenius Laboratory, Stockholm University, 10691 Stockholm, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Björnerås
authors.forename: Astrid
authors.initials: A
authors.lastname: Gräslund
authors.forename: Lena
authors.initials: L
authors.lastname: Mäler
mesh_terms: D002462:Cell Membrane / Q000378:metabolism*; D002942:Circular Dichroism; D004058:Diffusion; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D004399:Dynorphins / Q000737:chemistry*; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D010742:Phospholipid Ethers / Q000737:chemistry; D011487:Protein Conformation; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: C052298:1,2-dihexadecyl-sn-glycero-3-phosphocholine; D008051:Lipid Bilayers; D008823:Micelles; D010455:Peptides; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D010742:Phospholipid Ethers; D012997:Solvents; D014867:Water; D004399:Dynorphins; C002773:dimyristoylphosphatidylglycerol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; D004134:Dimyristoylphosphatidylcholine