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Gene Review

YPD1  -  Ypd1p

Saccharomyces cerevisiae S288c

Synonyms: D0790, Histidine-containing phosphotransfer protein YPD1, Phosphorelay intermediate protein YPD1, Tyrosine phosphatase-dependent protein 1, YDL235C
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Disease relevance of YPD1

  • The C-terminal response regulator domains of SLN1 and SSK1 and full-length YPD1 have been overexpressed and purified from E. coli [1].

High impact information on YPD1

  • Ypd1p binds to both Sln1p and Ssk1p and mediates the multistep phosphotransfer reaction (phosphorelay) [2].
  • The yeast "two-component" osmotic stress phosphorelay consists of the histidine kinase, Sln1p, the phosphorelay intermediate, Ypd1p and two response regulators, Ssk1p and Skn7p, whose activities are regulated by phosphorylation of a conserved aspartyl residue in the receiver domain [3].
  • The structure is composed of an up-down up-down four-helix bundle that is typical of histidine phosphotransfer or HPt domains such as Escherichia coli ArcB(C) and Saccharomyces cerevisiae Ypd1 [4].
  • The histidine-containing phosphotransfer (HPt) protein YPD1 is an osmoregulatory protein in yeast that facilitates phosphoryl transfer between the two response regulator domains associated with SLN1 and SSK1 [5].
  • The spy1(+) gene showed an ability to complement a mutational lesion of the Saccharomyces cerevisiae YPD1 gene, which is involved in an osmosensing signal transduction [6].

Biological context of YPD1


Associations of YPD1 with chemical compounds

  • Activation and control of the yeast HOG (High Osmolarity Glycerol) MAP kinase cascade is accomplished, in part, by a two-component sensory-response circuit comprised of the osmosensing histidine protein kinase Sln1p, the phospho-relay protein Ypd1p, and the response regulator protein Ssk1p [10].
  • In addition, we have examined the roles of several conserved amino acid residues surrounding the phosphorylatable histidine (H64) of YPD1 using phosphoryl transfer reactions involving YPD1 mutants [11].
  • The individual phosphoryl transfer reactions between YPD1 and the response regulator domains have been examined kinetically [11].
  • The Sln1p aspartyl phosphate is then transferred to Ypd1p, which in turn transfers the phosphoryl group to a conserved aspartate on one of two response regulators, Ssk1p and Skn7p [8].
  • Identification of YPD1, a gene of Candida albicans which encodes a two-component phosphohistidine intermediate protein [9].

Other interactions of YPD1

  • This phosphate is then sequentially transferred to Sln1p-Asp-1144, then to Ypd1p-His64, and finally to Ssk1p-Asp554 [2].
  • The SLN1-YPD1-SSK1 phosphorelay regulates a downstream mitogen-activated protein kinase cascade which ultimately controls the concentration of glycerol within the cell under hyperosmotic stress conditions [1].
  • These observations suggest that Hik1 is a direct target of the fungicides or is a mediator of fungicide action and that the fungicidal effect is transmitted to the Hog1 pathway via Ypd1 [12].

Analytical, diagnostic and therapeutic context of YPD1

  • Results from the yeast two-hybrid assay indicate that all three response regulator domains bind to a common area, largely hydrophobic in nature, on the surface of YPD1 [7].
  • Based on the crystal structure of YPD1 and the sequence alignment of YPD1 with other HPt domains, we site-specifically engineered and purified several YPD1 mutants in order to examine the role of conserved residues surrounding the phosphorylatable histidine (H64) [5].
  • Purification, crystallization and preliminary X-ray diffraction analysis of the yeast phosphorelay protein YPD1 [13].
  • In Saccharomyces cerevisiae, a phosphorelay signal transduction pathway composed of Sln1p, Ypd1p, and Ssk1p, which are homologous to bacterial two-component signal transducers, is involved in the osmosensing mechanism [14].


  1. Differential stabilities of phosphorylated response regulator domains reflect functional roles of the yeast osmoregulatory SLN1 and SSK1 proteins. Janiak-Spens, F., Sparling, J.M., Gurfinkel, M., West, A.H. J. Bacteriol. (1999) [Pubmed]
  2. Yeast HOG1 MAP kinase cascade is regulated by a multistep phosphorelay mechanism in the SLN1-YPD1-SSK1 "two-component" osmosensor. Posas, F., Wurgler-Murphy, S.M., Maeda, T., Witten, E.A., Thai, T.C., Saito, H. Cell (1996) [Pubmed]
  3. The eukaryotic two-component histidine kinase Sln1p regulates OCH1 via the transcription factor, Skn7p. Li, S., Dean, S., Li, Z., Horecka, J., Deschenes, R.J., Fassler, J.S. Mol. Biol. Cell (2002) [Pubmed]
  4. Crystal structure of the CheA histidine phosphotransfer domain that mediates response regulator phosphorylation in bacterial chemotaxis. Mourey, L., Da Re, S., Pédelacq, J.D., Tolstykh, T., Faurie, C., Guillet, V., Stock, J.B., Samama, J.P. J. Biol. Chem. (2001) [Pubmed]
  5. Functional roles of conserved amino acid residues surrounding the phosphorylatable histidine of the yeast phosphorelay protein YPD1. Janiak-Spens, F., West, A.H. Mol. Microbiol. (2000) [Pubmed]
  6. Spy1, a histidine-containing phosphotransfer signaling protein, regulates the fission yeast cell cycle through the Mcs4 response regulator. Aoyama, K., Mitsubayashi, Y., Aiba, H., Mizuno, T. J. Bacteriol. (2000) [Pubmed]
  7. A common docking site for response regulators on the yeast phosphorelay protein YPD1. Porter, S.W., West, A.H. Biochim. Biophys. Acta (2005) [Pubmed]
  8. Altered phosphotransfer in an activated mutant of the Saccharomyces cerevisiae two-component osmosensor Sln1p. Ault, A.D., Fassler, J.S., Deschenes, R.J. Eukaryotic Cell (2002) [Pubmed]
  9. Identification of YPD1, a gene of Candida albicans which encodes a two-component phosphohistidine intermediate protein. Calera, J.A., Herman, D., Calderone, R. Yeast (2000) [Pubmed]
  10. Yeast Skn7p activity is modulated by the Sln1p-Ypd1p osmosensor and contributes to regulation of the HOG pathway. Ketela, T., Brown, J.L., Stewart, R.C., Bussey, H. Mol. Gen. Genet. (1998) [Pubmed]
  11. Kinetic analysis of YPD1-dependent phosphotransfer reactions in the yeast osmoregulatory phosphorelay system. Janiak-Spens, F., Cook, P.F., West, A.H. Biochemistry (2005) [Pubmed]
  12. An Os-1 family histidine kinase from a filamentous fungus confers fungicide-sensitivity to yeast. Motoyama, T., Ohira, T., Kadokura, K., Ichiishi, A., Fujimura, M., Yamaguchi, I., Kudo, T. Curr. Genet. (2005) [Pubmed]
  13. Purification, crystallization and preliminary X-ray diffraction analysis of the yeast phosphorelay protein YPD1. Xu, Q., Nguyen, V., West, A.H. Acta Crystallogr. D Biol. Crystallogr. (1999) [Pubmed]
  14. Phosphorelay-regulated degradation of the yeast Ssk1p response regulator by the ubiquitin-proteasome system. Sato, N., Kawahara, H., Toh-e, A., Maeda, T. Mol. Cell. Biol. (2003) [Pubmed]
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