Variant-specific and reciprocal Hsp40 functions in Hsp104-mediated prion elimination

The amyloid-based prions of Saccharomyces cerevisiae are heritable aggregates of misfolded proteins, passed to daughter cells following fragmentation by molecular chaperones including the J-protein Sis1, Hsp70 and Hsp104. Overexpression of Hsp104 efficiently cures cell populations of the prion [PSI+] by an alternative Sis1-dependent mechanism that is currently the subject of significant debate. Here, we broadly investigate the role of J-proteins in this process by determining the impact of amyloid polymorphisms (prion variants) on the ability of well-studied Sis1 constructs to compensate for Sis1 and ask whether any other S. cerevisiae cytosolic J-proteins are also required for this process. Our comprehensive screen, examining all 13 members of the yeast cytosolic/nuclear J-protein complement, uncovered significant variant-dependent genetic evidence for a role of Apj1 (antiprion DnaJ) in this process. For strong, but not weak [PSI+] variants, depletion of Apj1 inhibits Hsp104-mediated curing. Overexpression of either Apj1 or Sis1 enhances curing, while overexpression of Ydj1 completely blocks it. We also demonstrated that Sis1 was the only J-protein necessary for the propagation of at least two weak [PSI+] variants and no J-protein alteration, or even combination of alterations, affected the curing of weak [PSI+] variants, suggesting the possibility of biochemically distinct, variant-specific Hsp104-mediated curing mechanisms.

Title	Variant-specific and reciprocal Hsp40 functions in Hsp104-mediated prion elimination
Creator	Kamiya, E.
	Astor, M. T.
	Sporn, Z. A.
	Berger, S. E.
	Hines, Justin K.
Publisher	Molecular Microbiology
Academic Department	Chemistry
Division	Natural Sciences
Organization	Lafayette College
Date Issued	July 2018
Date Available	2018-08-03T14:32:59Z
Type	Article
Language	English
Keyword	Structural basis
	Actin cytoskeleton
	Hsp70 chaperone
	Sup35 polymers
	Molecular chaperone Hsp104
	Saccharomyces cerevisiae PSI+
	Protein disaggregation
	Release factor
	Damaged proteins
	Yeast prion
Bibliographic Citation	Astor, M. T., et al. (2018 July) "Variant-specific and reciprocal Hsp40 functions in Hsp104-mediated prion elimination" Molecular Microbiology 109 (1): 41-62.
Standard Identifier	Handle 10385/2424
Standard Identifier	DOI 10.1111/mmi.13966
Permalink	http://hdl.handle.net/10385/2424
Rights Statement	Creative Commons - Attribution
Rights Holders	Kamiya, E.
	Astor, M. T.
	Sporn, Z. A.
	Berger, S. E.
	Hines, Justin K.