Identification and Structural Characterization of the Precursor Conformation of the Prion Protein which Directly Initiates Misfolding and Oligomerization.
To identify and structurally characterize the precursor conformation of the prion protein (PrP), from which misfolding and aggregation directly commence, has been a long-standing goal. Misfolding converts the α-helical, non-pathogenic functional form of PrP to pathogenic, β-structured oligomeric and amyloidogenic forms, which are the cause of prion diseases. Susceptibility to sporadic prion disease correlates well with the propensity of PrP to misfold to cytotoxic, proteinase K resistant oligomeric conformations at low pH. In this study, mutagenesis at the hydrophobic core of the mouse PrP has been shown to stabilize a monomeric unfolding intermediate (I), which is populated significantly at equilibrium at low pH. Importantly, the rate of formation of β-structured oligomers at low pH is found to correlate well with the extent to which this intermediate is populated. The misfolding process is limited by the dimerization of I, indicating that I is the monomeric precursor conformation that directly initiates misfolding. Structural and thermodynamic characterization by native-state hydrogen-deuterium exchange mass spectrometry studies indicate that the precursor conformation is a partially unfolded form of PrP that forms under misfolding-prone solvent conditions.
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India.
Roumita
R
Moulick
National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru 560065, India. Electronic address: jayant@ncbs.res.in.
Jayant B
JB
Udgaonkar
D000818:Animals; D004252:DNA Mutational Analysis; D006863:Hydrogen-Ion Concentration; D013058:Mass Spectrometry; D051379:Mice; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D000072002:Prion Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D066263:Protein Aggregation, Pathological; D011487:Protein Conformation; D017510:Protein Folding; D055503:Protein Multimerization; D013816:Thermodynamics
D050505:Mutant Proteins; D000072002:Prion Proteins; C512657:Prnp protein, mouse
hydrogen–deuterium exchange; mass spectrometry; misfolding; partially unfolded forms; prion