The Residue 129 Polymorphism in Human Prion Protein Does Not Confer Susceptibility to Creutzfeldt-Jakob Disease by Altering the Structure or Global Stability of PrPC (original) (raw)

2004, Journal of Biological Chemistry

There are two common forms of prion protein (PrP) in humans, with either methionine or valine at position 129. This polymorphism is a powerful determinant of the genetic susceptibility of humans toward both sporadic and acquired forms of prion disease and restricts propagation of particular prion strains. Despite its key role, we have no information on the effect of this mutation on the structure, stability, folding, and dynamics of the cellular form of PrP (PrP C). Here, we show that the mutation has no measurable effect on the folding, dynamics, and stability of PrP C. Our data indicate that the 129M/V polymorphism does not affect prion propagation through its effect on PrP C ; rather, its influence is likely to be downstream in the disease mechanism. We infer that the M/V effect is mediated through the conformation or stability of disease-related PrP (PrP Sc) or intermediates or on the kinetics of their formation. The prion diseases are a group of fatal neurodegenerative diseases that include scrapie in sheep and goats; bovine spongiform encephalopathy (BSE) 1 in cattle; and Creutzfeldt-Jakob disease (CJD), Gerstmann-Strä ussler-Scheinker disease, fatal familial insomnia (FFI), and kuru in humans. The human diseases may be inherited, arise sporadically, or be acquired through exposure to infectious prions (1, 2). Although rare in humans, intense interest has focused on these diseases both because of their unique biology and because of the occurrence of variant CJD, a new form of human prion disease, and the experimental evidence that it is caused by a BSE-like prion strain (3-5). According to the "protein-only" hypothesis (6), prions are composed principally or entirely of abnormal isoforms of hostencoded prion protein (PrP) (7). The disease-related isoform, PrP Sc , is derived from its normal cellular precursor, PrP C , by a