- THIS ARTICLE
- Full Text
- Full Text (PDF)
-
All Versions of this Article:
genetics.108.089458v1
179/3/1301 most recent - Alert me when this article is cited
- Alert me if a correction is posted
- SERVICES
- Email this article to a friend
- Similar articles in this journal
- Similar articles in PubMed
- Alert me to new issues of the journal
- Download to citation manager
- Reprints & Permissions
- CITING ARTICLES
- Citing Articles via HighWire
- Citing Articles via Google Scholar
- GOOGLE SCHOLAR
- Articles by Sharma, D.
- Articles by Masison, D. C.
- Search for Related Content
- PUBMED
- PubMed Citation
- Articles by Sharma, D.
- Articles by Masison, D. C.
Originally published as Genetics Published Articles Ahead of Print on June 18, 2008.
Genetics, Vol. 179, 1301-1311, July 2008, Copyright © 2008
doi:10.1534/genetics.108.089458
Functionally Redundant Isoforms of a Yeast Hsp70 Chaperone Subfamily Have Different Antiprion Effects
Deepak Sharma and Daniel C. Masison1
Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0851
1 Corresponding author: Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 8 Center Dr., Bldg. 8, Room 407, Bethesda, MD 20892-0851.
E-mail: masisond{at}helix.nih.gov
Why eukaryotes encode multiple Hsp70 isoforms is unclear. Saccharomyces cerevisiae Ssa1p and Ssa2p are constitutive 98% identical Hsp70's. Stress-inducible Ssa3p and Ssa4p are 80% identical to Ssa1/2p. We show Ssa1p-4p have distinct functions affecting [PSI+] and [URE3] prions. When expressed as the only Ssa, Ssa1p antagonized [URE3] and Ssa2p antagonized [PSI+]. Ssa3p and Ssa4p influenced [URE3] and [PSI+] somewhat differently but overall their effects paralleled those of Ssa1p and Ssa2p, respectively. Additionally, Ssa3p suppressed a prion-inhibitory effect of elevated temperature. Our previously described Ssa1-21p mutant weakens [PSI+] in SSA1-21 SSA2 cells and abolishes it in SSA1-21 ssa2
cells. To test if the same mutation affected other prions or altered Ssa2p similarly, we compared effects of a constructed Ssa2-21p mutant and Ssa1-21p on both prions. Surprisingly, [URE3] was unaffected in SSA1-21 SSA2 cells and could propagate in SSA1-21 ssa2 cells. Ssa2-21p impaired [URE3] considerably and weakened [PSI+] strongly but in a manner distinct from Ssa1-21p, highlighting functional differences between these nearly identical Hsp70's. Our data uncover exquisite functional differences among isoforms of a highly homologous cytosolic Hsp70 subfamily and point to a possibility that variations in Hsp70 function that might improve fitness under optimal conditions are also important during stress.
This article has been cited by other articles:
 |
|
 |
|
  J. Masel and C. K. Griswold The Strength of Selection Against the Yeast Prion [PSI+] Genetics, March 1, 2009; 181(3): 1057 - 1063. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Sharma, R. F. Stanley, and D. C. Masison Curing of Yeast [URE3] Prion by the Hsp40 Cochaperone Ydj1p Is Mediated by Hsp70 Genetics, January 1, 2009; 181(1): 129 - 137. [Abstract] [Full Text] [PDF]
|
|
|