NR AFUP
AU Inouye,H.; Bond,J.; Baldwin,M.A.; Ball,H.L.; Prusiner,S.B.; Kirschner,D.A.
TI Structural changes in a hydrophobic domain of the prion protein induced by hydration and by ala -> Val and pro -> Leu substitutions
QU Journal of Molecular Biology 2000 Jul 28; 300(5): 1283-96
PT journal article
AB X-ray diffraction was used to study the structure of assemblies formed by synthetic peptide fragments of the prion protein (PrP) that include the hydrophobic domain implicated in the Gerstmann-Sträussler-Scheinker (GSS) mutation (P102L). The effects of hydration on polypeptide assembly and of Ala -> Val substitutions in the hydrophobic domain were characterized. Synthetic peptides included: (i) Syrian hamster (SHa) hydrophobic core, SHa106-122 (KTNMKHMAGAAAAGAVV); (ii) SHa104-122(3A-V), with A -> V mutations at 113, 115 and 118 (KPKTNMKHMVGVAAVGAVV); (iii) mouse (Mo) wild-type sequence of the N-terminal hydrophobic domain, Mo89-143WT; and (iv) the same mouse sequence with leucine substitution for proline at residue number 101, Mo89-143(P101L). Samples of SHa106-122 that formed assemblies while drying under ambient conditions showed X-ray patterns indicative of 33 A thick slab-like structures having extensive H-bonding and intersheet stacking. By contrast, lyophilized peptide that was equilibrated against 100 % relative humidity showed assemblies with only a few layers of beta-sheets. The Ala -> Val substitutions in SHa104-122 and Mo89-143(P101L) resulted in the formation of 40 A wide, cross-beta fibrils. Observation of similar size beta-sheet fibrils formed by peptides SHa104-122(3A-V) and the longer Mo89-143(P101L) supports the notion that the hydrophobic sequence forms a template or core that promotes the beta-folding of the longer peptide. The substitution of amino acids in the mutants, e.g. 3A -> V and P101L, enhances the folding of the peptide into compact structural units, significantly enhancing the formation of the extensive beta-sheet fibrils.
MH Amino Acid Sequence; Amino Acid Substitution/*genetics; Animal; Gerstmann-Sträussler-Scheinker Disease/*genetics; Hamsters; Human; Hydrogen Bonding; Mesocricetus; Mice; Molecular Sequence Data; Mutation/genetics; Peptide Fragments/chemistry/genetics/metabolism; Prions/*chemistry/genetics/*metabolism; Protein Conformation; Protein Folding; Support, Non-U.S. Gov't; Support, U.S. Gov't, P.H.S.; Water/*metabolism; X-Ray Diffraction
AD Department of Biology, Boston College, Chestnut Hill, MA 02467-3811, USA. inouye@amy.bc.edu
SP englisch
PO England