Format

Send to

Choose Destination
EMBO J. 2007 Aug 22;26(16):3794-803. Epub 2007 Aug 2.

J-protein co-chaperone Sis1 required for generation of [RNQ+] seeds necessary for prion propagation.

Author information

1
Department of Biochemistry, University of Wisconsin, Madison, WI 53706-1544, USA.

Abstract

Yeast prions are protein-based genetic elements capable of self-perpetuation. One such prion, [RNQ(+)], requires the J-protein Sis1, an Ssa Hsp70 co-chaperone, as well as the AAA+ ATPase, Hsp104, for its propagation. We report that, upon depletion of Sis1, as well as upon inactivation of Hsp104, Rnq1 aggregates increased in size. Subsequently, cells having large aggregates, as well as an apparently soluble pool of Rnq1, became predominant in the cell population. Newly synthesized Rnq1 localized to both aggregates and bulk cytosol, suggesting that nascent Rnq1 partitioned into pools of prion and nonprion conformations, and implying that these large aggregates were still active as seeds. Ultimately, soluble Rnq1 predominated, and the prion was lost from the population. Our data suggest a model in which J-protein:Hsp70 machinery functions in prion propagation, in conjunction with Hsp104. Together, these chaperones facilitate fragmentation of prion polymers, generating a sufficient number of seeds to allow efficient conversion of newly synthesized Rnq1 into the prion conformation.

PMID:
17673909
PMCID:
PMC1952226
DOI:
10.1038/sj.emboj.7601811
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wiley Icon for PubMed Central
Loading ...
Support Center