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PPZ1  -  Ppz1p

Saccharomyces cerevisiae S288c

Synonyms: Serine/threonine-protein phosphatase PP-Z1, YM9571.02C, YML016C
 
 
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High impact information on PPZ1

  • The growth defect caused by overexpression of PPZ1 is intensified in strains with low G1 cyclin levels (such as bck2Delta or cln3Delta mutants), whereas mutation of PPZ1 rescues the synthetic lethal phenotype of sit4 cln3 mutants [1].
  • The PPZ2 gene is predicted to encode a type 1-related protein phosphatase and is functionally redundant with a closely related gene, designated PPZ1 [2].
  • PPZ1 is also important for cell integrity, as ppz1Delta cells undergo lysis under caffeine stress and PPZ1 overexpression overrides the lytic defect of mutants in the protein kinase C/mitogen-activated protein (MAP) kinase pathway [3].
  • We have isolated two Arabidopsis thaliana genes, AtHAL3a and AtHAL3b, showing homology with HAL3, a yeast protein which regulates the cell cycle and tolerance to salt stress through inhibition of the PPZ1 type-1 protein phosphatase [4].
  • Genetic interactions between GLC7, PPZ1 and PPZ2 in saccharomyces cerevisiae [5].
 

Biological context of PPZ1

  • The SAL6 gene encodes a very basic 549-amino acid protein whose C-terminal catalytic region of 265 residues is 63% identical to serine/threonine PP1 phosphatases, and 66% identical to yeast PPZ1 and PPZ2 phosphatases [6].
  • Haploid cells carrying a double disruption of PPZ1 and PPZ2 genes also show a marked increase in cell size and cell lysis, which can be significantly reduced by the addition of 1 M sorbitol to the growth medium [7].
  • Furthermore, high copy number expression of PZL-1 alleviated the lytic phenotype of a S. cerevisiae slt2/mpk1 mitogen-activated protein (MAP) kinase mutant, similarly to that described for PPZ1, and mimicked the effects of high levels of Ppz1 on cell growth [8].
  • PPZ1 and PPZ2 are two novel yeast phosphatases showing 93% amino acid sequence identity to one another [9].
 

Anatomical context of PPZ1

  • Given these observations and the fact that K+ is the major determinant of intracellular turgor pressure, we reasoned that the connection between PPZ1 and -2 and MPK1 was due to the combination of increased internal turgor pressure in Ppz-deficient strains and cell wall instability observed in strains lacking MPK1 [10].
 

Associations of PPZ1 with chemical compounds

  • When expressed in high-copy number from the PPZ1 promoter, the pzh1 ORF rescues the caffeine-induced lytic defect and slightly decreases the high salt tolerance of S. cerevisiae ppz1delta mutants [11].
  • The protein consists of two distinct domains: the carboxy-terminal phosphatase domain is approximately 60% identical to either PP1 or the carboxy-terminal domains of PPZ1 and PPZ2, while the amino-terminal region is rich in serine and asparagine [12].
  • Expression of PZL-1 in S. cerevisiae from the PPZ1 promoter was able to rescue the altered sensitivity to caffeine and lithium ions of a ppz1 strain [8].
 

Regulatory relationships of PPZ1

  • Moreover, the expression of genes previously identified as targets of the Mpk1 pathway are also up-regulated in strains lacking PPZ1 and -2 [10].

References

  1. The yeast ser/thr phosphatases sit4 and ppz1 play opposite roles in regulation of the cell cycle. Clotet, J., Garí, E., Aldea, M., Ariño, J. Mol. Cell. Biol. (1999) [Pubmed]
  2. A pair of functionally redundant yeast genes (PPZ1 and PPZ2) encoding type 1-related protein phosphatases function within the PKC1-mediated pathway. Lee, K.S., Hines, L.K., Levin, D.E. Mol. Cell. Biol. (1993) [Pubmed]
  3. The NH2-terminal extension of protein phosphatase PPZ1 has an essential functional role. Clotet, J., Posas, F., de Nadal, E., Ariño, J. J. Biol. Chem. (1996) [Pubmed]
  4. Arabidopsis thaliana AtHAL3: a flavoprotein related to salt and osmotic tolerance and plant growth. Espinosa-Ruiz, A., Bellés, J.M., Serrano, R., Culiáñez-MacIà, F.A. Plant J. (1999) [Pubmed]
  5. Genetic interactions between GLC7, PPZ1 and PPZ2 in saccharomyces cerevisiae. Venturi, G.M., Bloecher, A., Williams-Hart, T., Tatchell, K. Genetics (2000) [Pubmed]
  6. The yeast translational allosuppressor, SAL6: a new member of the PP1-like phosphatase family with a long serine-rich N-terminal extension. Vincent, A., Newnam, G., Liebman, S.W. Genetics (1994) [Pubmed]
  7. Both isoforms of protein phosphatase Z are essential for the maintenance of cell size and integrity in Saccharomyces cerevisiae in response to osmotic stress. Hughes, V., Müller, A., Stark, M.J., Cohen, P.T. Eur. J. Biochem. (1993) [Pubmed]
  8. Functional analysis of the Neurospora crassa PZL-1 protein phosphatase by expression in budding and fission yeast. Vissi, E., Clotet, J., de Nadal, E., Barceló, A., Bakó , E., Gergely, P., Dombrádi, V., Ariño, J. Yeast (2001) [Pubmed]
  9. Protein phosphatase 2Bw and protein phosphatase Z are Saccharomyces cerevisiae enzymes. Da Cruz e Silva, E.F., Hughes, V., McDonald, P., Stark, M.J., Cohen, P.T. Biochim. Biophys. Acta (1991) [Pubmed]
  10. Response of the Saccharomyces cerevisiae Mpk1 mitogen-activated protein kinase pathway to increases in internal turgor pressure caused by loss of Ppz protein phosphatases. Merchan, S., Bernal, D., Serrano, R., Yenush, L. Eukaryotic Cell (2004) [Pubmed]
  11. Regulation of salt tolerance in fission yeast by a protein-phosphatase-Z-like Ser/Thr protein phosphatase. Balcells, L., Gómez, N., Casamayor, A., Clotet, J., Ariño, J. Eur. J. Biochem. (1997) [Pubmed]
  12. PPQ, a novel protein phosphatase containing a Ser + Asn-rich amino-terminal domain, is involved in the regulation of protein synthesis. Chen, M.X., Chen, Y.H., Cohen, P.T. Eur. J. Biochem. (1993) [Pubmed]
 
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