Chaperonin-mediated de novo generation of prion protein aggregates.
The infectious prion protein, PrP(Sc), a predominantly beta-sheet aggregate, is derived from PrP(C), the largely alpha-helical cellular isoform of PrP. Conformational conversion of PrP(C) into PrP(Sc) has been suggested to involve a chaperone-like factor. Here we report that the bacterial chaperonin GroEL, a close homolog of eukaryotic Hsp60, can catalyze the aggregation of chemically denatured and of folded, recombinant PrP in a model reaction in vitro. Aggregates form upon ATP-dependent release of PrP from chaperonin and have certain properties of PrP(Sc), including a high beta-sheet content, the ability to bind the dye Congo red, detergent-insolubility and increased protease-resistance. A conserved sequence segment of PrP (residues 90-121), critical for PrP(Sc) generation in vivo, is also required for chaperonin-mediated aggregate formation in vitro. Initial binding of refolded, alpha-helical PrP to chaperonin is mediated by the unstructured N-terminal segment of PrP (residues 23-121) and is followed by a rearrangement of the globular PrP core-domain. These results show that chaperonins of the Hsp60 class can, in principle, mediate PrP aggregation de novo, i.e. independently of a pre-existent PrP(Sc) template.
Stöckel
J
J
Department of Cellular Biochemistry, Max-Planck-Institute of Biochemistry, Martinsried, D-82152, Germany.
Hartl
F U
FU
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D018835:Chaperonin 10 / Q000737:chemistry / Q000378:metabolism; D018834:Chaperonin 60 / Q000737:chemistry / Q000378:metabolism; D018833:Chaperonins / Q000737:chemistry / Q000378:metabolism*; D003224:Congo Red / Q000378:metabolism; D017124:Conserved Sequence; D010450:Endopeptidases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008954:Models, Biological; D011328:Prions / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D020673:Protein Renaturation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D012995:Solubility
D018835:Chaperonin 10; D018834:Chaperonin 60; D011328:Prions; D011993:Recombinant Fusion Proteins; D003224:Congo Red; D000255:Adenosine Triphosphate; D010450:Endopeptidases; D018833:Chaperonins