Chaperoning prions: the cellular machinery for propagating an infectious protein?
Newly made polypeptide chains require the help of molecular chaperones not only to rapidly reach their final three-dimensional forms, but also to unfold and then correctly refold them back to their biologically active form should they misfold. Most prions are an unusual type of protein that can exist in one of two stable conformations, one of which leads to formation of an infectious alternatively folded form. Studies in Baker's yeast (Saccharomyces cerevisiae) have revealed that prions can exploit the molecular chaperone machinery in the cell in order to ensure stable propagation of the infectious, aggregation-prone form. The disaggregation of yeast prion aggregates by molecular chaperones generates forms of the prion protein that can seed the protein polymerisation that underlies the prion propagation cycle. In this article, we review what we have learnt about the role of molecular chaperones in yeast prion propagation, describe a model that can explain the role of various classes of molecular chaperones and their co-chaperones, and speculate on the possible involvement of chaperones in the propagation of mammalian prions.
Jones
Gary W
GW
Department of Biology, National University of Ireland, Maynooth, Co. Kildare Ireland. garyjones@nuim.ie
Tuite
Mick F
MF
D003600:Cytosol / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000378:metabolism; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D046911:Macromolecular Substances / Q000737:chemistry; D008954:Models, Biological; D018832:Molecular Chaperones / Q000737:chemistry / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011328:Prions / Q000737:chemistry / Q000502:physiology*; D011489:Protein Denaturation; D017510:Protein Folding; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism
D005656:Fungal Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D010455:Peptides; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; C070972:HsP104 protein, S cerevisiae; D049452:Green Fluorescent Proteins