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Gene Review

SSA1  -  Hsp70 family ATPase SSA1

Saccharomyces cerevisiae S288c

Synonyms: Heat shock protein SSA1, Heat shock protein YG100, YAL005C
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High impact information on SSA1


Biological context of SSA1

  • Strains carrying deletions in both the SSA1 and SSA2 HSP70 genes of Saccharomyces cerevisiae exhibit pleiotropic phenotypes, including the inability to grow at 37 degrees C or higher, reduced growth rate at permissive temperatures, increased HSP gene expression, and constitutive thermotolerance [6].
  • The nucleotide sequence of this latter region is very similar to essential sequences within the URS elements from the yeast CAR1 and SSA1 genes, respectively [7].
  • To determine the significance of each of these sequences for expression of SSA1, we analyzed expression from a set of promoters containing point mutations in each of the HSEs, individually and in pairwise combinations [8].
  • Each chimeric gene was composed of promoter and N-terminal coding regions from the yeast SSA1 or SSA2 genes fused in-frame to the lac operon [9].
  • However, in combination with a deletion of SSA1, ssa2-10 eliminates the nonsense-suppression phenotype of [PSI(+)] cells [10].

Anatomical context of SSA1

  • Mutation of the ATP-binding pocket of SSA1 indicates that a functional interaction between Ssa1p and Ydj1p is required for post-translational translocation into the yeast endoplasmic reticulum [11].

Associations of SSA1 with chemical compounds

  • Yeast cells were transformed with plasmids containing the SSA1 or SSA4 gene which was placed under the control of a galactose-inducible GAL1 promoter [12].

Physical interactions of SSA1

  • MFA2 is specifically stabilized in a strain bearing a temperature-sensitive mutation in the SSA1 gene [13].
  • Efficient translation of an SSA1-derived heat-shock mRNA in yeast cells limited for cap-binding protein and eIF-4F [14].

Other interactions of SSA1

  • Results show that, among the four major cytoplasmic isoenzymes produced in wild-type yeast, almost all of the activity is associated with the SSA1 and SSA2 isoenzymes [15].
  • We show that expression of the yeast GSH1 gene (encoding gamma-glutamylcysteine synthetase) and the SSA1 gene (encoding an HSP70 isoform) are induced by oxidants [16].
  • Expression of SSA1 reversed these effects, whereas co-expression of SSA1 and PDE2 restored high accumulation [17].
  • In a strain deleted for SSA1 and SSA2, we observed a reduced cellular content of Cdc25p [17].
  • In addition, a strain containing a single functional SSA gene, SSA1, and a deletion of YDJ1 accumulated the precursor form of alpha-factor [18].

Analytical, diagnostic and therapeutic context of SSA1


  1. Regulation of mRNA export in response to stress in Saccharomyces cerevisiae. Saavedra, C., Tung, K.S., Amberg, D.C., Hopper, A.K., Cole, C.N. Genes Dev. (1996) [Pubmed]
  2. Transcriptional regulation of a yeast HSP70 gene by heat shock factor and an upstream repression site-binding factor. Park, H.O., Craig, E.A. Genes Dev. (1991) [Pubmed]
  3. Stress and developmental regulation of the yeast C-type cyclin Ume3p (Srb11p/Ssn8p). Cooper, K.F., Mallory, M.J., Smith, J.B., Strich, R. EMBO J. (1997) [Pubmed]
  4. Folding in vivo of a newly translated yeast cytosolic enzyme is mediated by the SSA class of cytosolic yeast Hsp70 proteins. Kim, S., Schilke, B., Craig, E.A., Horwich, A.L. Proc. Natl. Acad. Sci. U.S.A. (1998) [Pubmed]
  5. Propagation of Saccharomyces cerevisiae [PSI+] prion is impaired by factors that regulate Hsp70 substrate binding. Jones, G., Song, Y., Chung, S., Masison, D.C. Mol. Cell. Biol. (2004) [Pubmed]
  6. A heat shock transcription factor with reduced activity suppresses a yeast HSP70 mutant. Halladay, J.T., Craig, E.A. Mol. Cell. Biol. (1995) [Pubmed]
  7. The upstream repression sequence from the yeast enolase gene ENO1 is a complex regulatory element that binds multiple trans-acting factors including REB1. Carmen, A.A., Holland, M.J. J. Biol. Chem. (1994) [Pubmed]
  8. Saccharomyces cerevisiae HSP70 heat shock elements are functionally distinct. Young, M.R., Craig, E.A. Mol. Cell. Biol. (1993) [Pubmed]
  9. Expression of lacZ gene fusions affects downstream transcription in yeast. Barnes, C.A., Johnston, G.C., Singer, R.A. Gene (1991) [Pubmed]
  10. [URE3] prion propagation is abolished by a mutation of the primary cytosolic Hsp70 of budding yeast. Roberts, B.T., Moriyama, H., Wickner, R.B. Yeast (2004) [Pubmed]
  11. Mutation of the ATP-binding pocket of SSA1 indicates that a functional interaction between Ssa1p and Ydj1p is required for post-translational translocation into the yeast endoplasmic reticulum. McClellan, A.J., Brodsky, J.L. Genetics (2000) [Pubmed]
  12. Thermal response of yeast cells overexpressing hsp70 genes. Weitzel, G., Li, G.C. International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group. (1993) [Pubmed]
  13. A yeast homologue of Hsp70, Ssa1p, regulates turnover of the MFA2 transcript through its AU-rich 3' untranslated region. Duttagupta, R., Vasudevan, S., Wilusz, C.J., Peltz, S.W. Mol. Cell. Biol. (2003) [Pubmed]
  14. Efficient translation of an SSA1-derived heat-shock mRNA in yeast cells limited for cap-binding protein and eIF-4F. Barnes, C.A., MacKenzie, M.M., Johnston, G.C., Singer, R.A. Mol. Gen. Genet. (1995) [Pubmed]
  15. Uncoating of coated vesicles by yeast hsp70 proteins. Gao, B.C., Biosca, J., Craig, E.A., Greene, L.E., Eisenberg, E. J. Biol. Chem. (1991) [Pubmed]
  16. The role of the YAP1 and YAP2 genes in the regulation of the adaptive oxidative stress responses of Saccharomyces cerevisiae. Stephen, D.W., Rivers, S.L., Jamieson, D.J. Mol. Microbiol. (1995) [Pubmed]
  17. Ssa1p chaperone interacts with the guanine nucleotide exchange factor of ras Cdc25p and controls the cAMP pathway in Saccharomyces cerevisiae. Geymonat, M., Wang, L., Garreau, H., Jacquet, M. Mol. Microbiol. (1998) [Pubmed]
  18. Functional interaction of cytosolic hsp70 and a DnaJ-related protein, Ydj1p, in protein translocation in vivo. Becker, J., Walter, W., Yan, W., Craig, E.A. Mol. Cell. Biol. (1996) [Pubmed]
  19. The stress response against denatured proteins in the deletion of cytosolic chaperones SSA1/2 is different from heat-shock response in Saccharomyces cerevisiae. Matsumoto, R., Akama, K., Rakwal, R., Iwahashi, H. BMC Genomics (2005) [Pubmed]
  20. Candida albicans Ssa1/2p is the cell envelope binding protein for human salivary histatin 5. Li, X.S., Reddy, M.S., Baev, D., Edgerton, M. J. Biol. Chem. (2003) [Pubmed]
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