Hydrogen/deuterium exchange mass spectrometry identifies two highly protected regions in recombinant full-length prion protein amyloid fibrils.
Understanding the structural basis that distinguishes the amyloid form of the prion protein from its monomeric homologue is of crucial importance to elucidate the mechanism of the lethal diseases related to this protein. Recently, an in vitro conversion system was established which reproduces the transition of recombinant prion protein PrP(23-230) from its native alpha-helical rich form into an aggregated amyloid beta-sheet rich form with physicochemical properties reminiscent to those of the disease-related isoform of the prion protein, PrPSc. To study the tertiary and quaternary structural organization within recombinant amyloid fibrils from mouse, mPrP(23-231)betaf; bovine, bPrP(23-230)betaf; and elk, ePrP(23-230)betaf; we utilized hydrogen/deuterium (H/D) exchange analyzed by matrix-assisted laser desorption/ionization (MALDI) and nano-electrospray (nano-ESI) mass spectrometry. No significant differences were found by measuring the deuterium exchange kinetics of the aggregated fibrillar forms for mPrP(23-231)betaf, bPrP(23-230)betaf and ePrP(23-230)betaf, indicating a similar overall structural organization of the fibrils from all three species. Next, we characterized the solvent accessibility for the soluble and fibrillar forms of the mouse prion protein by hydrogen exchange, pepsin proteolysis and nano-ESI ion trap mass spectrometry analysis. In its amyloid form, two highly protected regions of mPrP(23-231) comprising residues [24-98] and [182-212] were identified. The residues between the two highly protected stretches were found to be more solvent exposed, but less than in the soluble protein, and might therefore rather form part of a fibrillar interface.
Nazabal
Alexis
A
Department of Chemistry and Applied Biosciences, ETH Zurich, Wolfgang Pauli Strasse 10, 8093 Zürich, Switzerland.
Hornemann
Simone
S
Aguzzi
Adriano
A
Zenobi
Renato
R
D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D000818:Animals; D002417:Cattle; D003670:Deer; D041961:Deuterium Exchange Measurement; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011328:Prions / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000682:Amyloid; D010446:Peptide Fragments; D011328:Prions; D011994:Recombinant Proteins; C428437:prion protein (23-231)