Chaperone-supervised conversion of prion protein to its protease-resistant form.
Transmissible spongiform encephalopathies (TSEs) are lethal, infectious disorders of the mammalian nervous system. A TSE hallmark is the conversion of the cellular protein PrPC to disease-associated PrPSc (named for scrapie, the first known TSE). PrPC is protease-sensitive, monomeric, detergent soluble, and primarily alpha-helical; PrPSc is protease-resistant, polymerized, detergent insoluble, and rich in beta-sheet. The "protein-only" hypothesis posits that PrPSc is the infectious TSE agent that directly converts host-encoded PrPC to fresh PrPSc, harming neurons and creating new agents of infection. To gain insight on the conformational transitions of PrP, we tested the ability of several protein chaperones, which supervise the conformational transitions of proteins in diverse ways, to affect conversion of PrPC to its protease-resistant state. None affected conversion in the absence of pre-existing PrPSc. In its presence, only two, GroEL and Hsp104 (heat shock protein 104), significantly affected conversion. Both promoted it, but the reaction characteristics of conversions with the two chaperones were distinct. In contrast, chemical chaperones inhibited conversion. Our findings provide new mechanistic insights into nature of PrP conversions, and provide a new set of tools for studying the process underlying TSE pathogenesis.
DebBurman
S K
SK
Department of Molecular Genetics and Cell Biology, Howard Hughes Medical Institute, University of Chicago, Chicago, IL 60637, USA.
Raymond
G J
GJ
Caughey
B
B
Lindquist
S
S
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002474:Cell-Free System; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D006224:Cricetinae; D010450:Endopeptidases / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism*; D018621:PrPC Proteins / Q000737:chemistry / Q000378:metabolism*; D018620:PrPSc Proteins / Q000737:chemistry / Q000378:metabolism*; D017096:Prion Diseases / Q000209:etiology / Q000378:metabolism; D011489:Protein Denaturation; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D029701:Saccharomyces cerevisiae Proteins
D018835:Chaperonin 10; D018834:Chaperonin 60; D005656:Fungal Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D018621:PrPC Proteins; D018620:PrPSc Proteins; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D000255:Adenosine Triphosphate; D010450:Endopeptidases