NMR Solution Structure and Membrane Interaction of the N-Terminal Sequence (1−30) of the Bovine Prion Protein

Abstract

The structure and membrane interaction of the N-terminal sequence (1-30) of the bovine prion protein (bPrPp) has been investigated by NMR spectroscopy in phospholipid membrane mimetic systems. CD spectroscopy revealed that the peptide adopts a largely alpha-helical structure in zwitterionic bicelles as well as in DHPC micelles but has a less degree of alpha-helix structure in partly charged bicelles. The solution structure of bPrPp was determined in DHPC micelles, and an alpha-helix was found between residues Ser8 and Ile21. The residues within the helical region show slow amide hydrogen exchange. Translational diffusion measurements in zwitterionic q = 0.5 bicelles show that the peptide does not induce aggregation of the bicelles. Increased quadrupolar splittings were observed in the outer part of the (2)H spectrum of DMPC in q = 3.5 bicelles, indicating that the peptide induces a certain degree of order in the bilayer. The amide hydrogen exchange and the (2)H NMR results are consistent with a slight positive hydrophobic mismatch and that bPrPp forms a stable helix that inserts in a transmembrane location in the bilayer. The structure of bPrPp and its position in the membrane may be relevant for the understanding of how the N-terminal (1-30) part of the bovine PrP functions as a cell-penetrating peptide. These findings may lead to a better understanding of how the prion protein accumulates at the membrane surface and also how the conversion into the scrapie form is carried out.

High Cationic Charge and Bilayer Interface-Binding Helices in a Regulatory Lipid Glycosyltransferase,

“…This translates to an estimated R-helix content of 43% in the DHPC solution, 31% in a zwitterionic (i.e., PC) bicelle solution, and 36% in an anionic bicelle solution (i.e., with PG), respectively. A somewhat larger amount of helix is thus observed in DHPC micelles, which agrees with previous observations for peptides in different solvents (33). The absolute amount of helix is, however, difficult to determine quantitatively because differences in solubility and background may influence the spectra.…”

Resolving the paradox for protein aggregation diseases: NMR structure and dynamics of the membrane-embedded P56S-MSP causing ALS imply a common mechanism for aggregation-prone proteins to attack membranes

“…Interestingly, partly-soluble proteins, causing various human diseases, have also been shown to attack membranes by transforming their unstructured states in aqueous solution, to amphiphilic helixes in membranes. These proteins include: prions of spongiform transmissible encephalopathies 70, 71 , amyloid beta-(1–40) and beta-(1–42) peptides of Alzheimer’s disease 72, 73 , tau tangles of Alzheimer’s disease 74 , α-synuclein of Parkinson’s disease 62, 64, 65 , huntingtin of Huntington’s disease 75– 77 and the islet amyloid polypeptide of type II diabetes 5, 7 .…”

The Magic of Bicelles Lights Up Membrane Protein Structure

“…174 Similarly, for the N-terminal fragment (1–30) of bovine prion protein, a peptide with cell-penetrating properties, deuterium exchange in isotropic as well as 2 H NMR splittings in oriented bicelles indicate a transmembrane orientation with slight hydrophobic mismatch. 175 For the mitochondrial F 1 β presequence from Nicotinia plumbagigifolia an NMR solution structure was determined, and differences between the induced α-helical structure in neutral and acidic bicelles were described. 176 Relaxation rate measurements on the influenza hemagglutinin fusion peptide embedded in different size isotropic bicelles revealed an overall rocking motion of the membrane-bound peptide.…”