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Gene Review

SSA3  -  Hsp70 family ATPase SSA3

Saccharomyces cerevisiae S288c

Synonyms: Heat shock protein SSA3, YBL06.07, YBL0610, YBL075C
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High impact information on SSA3

  • TOP1-dependent repression operates even on HSP26 and SSA3, which have been shown previously to be transcriptionally induced in early stationary phase [1].
  • Here, we show that the zinc finger protein Gis1 acts as a dosage-dependent suppressor of the rim15Delta defect in nutrient limitation-induced transcriptional derepression of SSA3 [2].
  • A 35 bp region of SSA3, distinct from UASHS, contains sequences capable of activating a heterologous promoter following the diauxic shift and in the stationary phase of the yeast life cycle; this region has been designated an upstream activating sequence, UASPDS [3].
  • Alterations in Sok2 protein production also affect the expression of genes involved in several other PKA-regulated processes, including glycogen accumulation (GAC1) and heat shock resistance (SSA3) [4].
  • The ability to drive basal transcription is not inherent in all natural HSEs, since the HSEs from the heat-inducible SSA3 and SSA4 genes showed no basal activity when placed in the CYC1 vector [5].

Biological context of SSA3

  • The EXA1-1 suppressor mutation thus improves the growth of ssa1 ssa2 strains by selectively increasing HSF-mediated expression of SSA3 [6].
  • These results show that two glucose-dependent signalling pathways, which can be distinguished on the basis of their requirement for glucose phosphorylation, appear to be involved in activation of trehalase, repression of CTT1 and SSA3 and induction of ribosomal protein genes [7].
  • The SSA3 gene of Saccharomyces cerevisiae, a member of the HSP70 multigene family, is expressed at low levels under optimal growth conditions and is dramatically induced in response to heat shock [8].
  • One subfamily, identified by sequence homology, contains four genes, SSA1, SSA2, SSA3, and SSA4 (formerly YG100, YG102, YG106, and YG107, respectively) [9].
  • Strains carrying the AAP1 gene on a high copy plasmid show an increase in the major arginine/alanine aminopeptidase activity, a dramatic increase in glycogen accumulation, and an increase in transcription from a vector carrying lacZ fused to the promoter of a gene (SSA3) expressed during post-diauxic and stationary phases of the culture cycle [10].

Associations of SSA3 with chemical compounds

  • SSA3 RNA accumulation was higher in sporulating cells than in nonsporulating cells and was reversed by addition of glucose [11].
  • Studies with cyr1 mutants indicated that SSA3 RNA accumulation is stimulated by decreasing intracellular cyclic AMP concentrations [11].
  • However, during fermentative growth only TSL1 shows an expression pattern like that of the STRE-controlled genes CTT1 and SSA3, while expression of the three other trehalose synthase genes is only transiently down-regulated [12].

Regulatory relationships of SSA3

  • SSA3, like SSA4, is a heat-inducible gene that is not normally expressed at 23 degrees C. Nevertheless, an intact copy of SSA3 regulated by the constitutive SSA2 promoter was capable of rescuing a ssa1 ssa2 ssa4 strain [9].

Other interactions of SSA3

  • In exa2-1 ssa1 ssa2 strains the gene products of the remaining SSA hsp70 genes, SSA3 and SSA4 (Ssa3/4p), accumulate to higher levels [13].
  • Consistent with this hypothesis, EXA3-1 is tightly linked to HSF1, the gene encoding the transcriptional regulatory protein known as "heat shock factor." All of the genes identified in this study seem to be involved in regulating the expression of SSA3 and SSA4 or the activity of their protein products [13].
  • Loss of function of Sin1p leads to overexpression of SSA3 in the ssa1 ssa2 mutant background, at a level which is sufficient to mediate suppression [6].
  • Repression of CTT1 and SSA3 under the same conditions was also largely dependent on the presence of the sugar and also in these cases there was a strong effect when the sugar could not be phosphorylated [7].
  • Here we present the nucleotide sequence of the SSA3 and SSB2 genes, completing the nucleotide sequence data for the yeast HSP70 family [14].

Analytical, diagnostic and therapeutic context of SSA3


  1. A general topoisomerase I-dependent transcriptional repression in the stationary phase in yeast. Choder, M. Genes Dev. (1991) [Pubmed]
  2. Saccharomyces cerevisiae Ras/cAMP pathway controls post-diauxic shift element-dependent transcription through the zinc finger protein Gis1. Pedruzzi, I., Bürckert, N., Egger, P., De Virgilio, C. EMBO J. (2000) [Pubmed]
  3. Regulation of a yeast HSP70 gene by a cAMP responsive transcriptional control element. Boorstein, W.R., Craig, E.A. EMBO J. (1990) [Pubmed]
  4. SOK2 may regulate cyclic AMP-dependent protein kinase-stimulated growth and pseudohyphal development by repressing transcription. Ward, M.P., Gimeno, C.J., Fink, G.R., Garrett, S. Mol. Cell. Biol. (1995) [Pubmed]
  5. Saccharomyces cerevisiae HSP70 heat shock elements are functionally distinct. Young, M.R., Craig, E.A. Mol. Cell. Biol. (1993) [Pubmed]
  6. Suppression of an Hsp70 mutant phenotype in Saccharomyces cerevisiae through loss of function of the chromatin component Sin1p/Spt2p. Baxter, B.K., Craig, E.A. J. Bacteriol. (1998) [Pubmed]
  7. Glucose-triggered signalling in Saccharomyces cerevisiae: different requirements for sugar phosphorylation between cells grown on glucose and those grown on non-fermentable carbon sources. Pernambuco, M.B., Winderickx, J., Crauwels, M., Griffioen, G., Mager, W.H., Thevelein, J.M. Microbiology (Reading, Engl.) (1996) [Pubmed]
  8. Transcriptional regulation of SSA3, an HSP70 gene from Saccharomyces cerevisiae. Boorstein, W.R., Craig, E.A. Mol. Cell. Biol. (1990) [Pubmed]
  9. Complex interactions among members of an essential subfamily of hsp70 genes in Saccharomyces cerevisiae. Werner-Washburne, M., Stone, D.E., Craig, E.A. Mol. Cell. Biol. (1987) [Pubmed]
  10. Isolation and characterization of AAP1. A gene encoding an alanine/arginine aminopeptidase in yeast. Caprioglio, D.R., Padilla, C., Werner-Washburne, M. J. Biol. Chem. (1993) [Pubmed]
  11. Yeast Hsp70 RNA levels vary in response to the physiological status of the cell. Werner-Washburne, M., Becker, J., Kosic-Smithers, J., Craig, E.A. J. Bacteriol. (1989) [Pubmed]
  12. Regulation of genes encoding subunits of the trehalose synthase complex in Saccharomyces cerevisiae: novel variations of STRE-mediated transcription control? Winderickx, J., de Winde, J.H., Crauwels, M., Hino, A., Hohmann, S., Van Dijck, P., Thevelein, J.M. Mol. Gen. Genet. (1996) [Pubmed]
  13. Isolation and characterization of extragenic suppressors of mutations in the SSA hsp70 genes of Saccharomyces cerevisiae. Nelson, R.J., Heschl, M.F., Craig, E.A. Genetics (1992) [Pubmed]
  14. Molecular evolution of the HSP70 multigene family. Boorstein, W.R., Ziegelhoffer, T., Craig, E.A. J. Mol. Evol. (1994) [Pubmed]
  15. The two genes encoding yeast ribosomal protein S8 reside on different chromosomes, and are closely linked to the hsp70 stress protein genes SSA3 and SSA4. Logghe, M., Molemans, F., Fiers, W., Contreras, R. Yeast (1994) [Pubmed]
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