Role of Ptc2 Type 2C Ser/Thr Phosphatase in Yeast High-Osmolarity Glycerol Pathway Inactivation

Young, Christian D.; Mapes, James; Hanneman, Jennifer; Al-Zarban, Sheikha; Ota, Irene M.

doi:10.1128/ec.1.6.1032-1040.2002

Cited by 76 publications

(75 citation statements)

References 43 publications

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“…1B, compare lines 1 and 7 to 8). Of importance, the point mutation T376A is unlikely to affect Ptc2 catalytic activity since the truncation mutant protein Ptc2(1-355) has a wild-type phosphatase activity in vitro (55). We also verified that the T376A mutation did not reduce the expression level of the Gal4BD-Ptc2(1-428) construct (Fig.…”

Section: Ptc2 Threonine T376 Is Required For the Interaction Betweensupporting

confidence: 51%

Mechanisms of Checkpoint Kinase Rad53 Inactivation after a Double-Strand Break in Saccharomyces cerevisiae

Guillemain

Mauger

et al. 2007

Molecular and Cellular Biology

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In Saccharomyces cerevisiae, double-strand breaks (DSBs) activate DNA checkpoint pathways that trigger several responses including a strong G 2 /M arrest. We have previously provided evidence that the phosphatases Ptc2 and Ptc3 of the protein phosphatase 2C type are required for DNA checkpoint inactivation after a DSB and probably dephosphorylate the checkpoint kinase Rad53. In this article we have investigated further the interactions between Ptc2 and Rad53. We showed that forkhead-associated domain 1 (FHA1) of Rad53 interacts with a specific threonine of Ptc2, T376, located outside its catalytic domain in a TXXD motif which constitutes an optimal FHA1 binding sequence in vitro. Mutating T376 abolishes Ptc2 interaction with the Rad53 FHA1 domain and results in adaptation and recovery defects following a DSB. We found that Ckb1 and Ckb2, the regulatory subunits of the protein kinase CK2, are necessary for the in vivo interaction between Ptc2 and the Rad53 FHA1 domain, that Ckb1 binds Ptc2 in vitro and that ckb1⌬ and ckb2⌬ mutants are defective in adaptation and recovery after a DSB. Our data thus strongly suggest that CK2 is the kinase responsible for the in vivo phosphorylation of Ptc2 T376.The DNA checkpoint is a surveillance mechanism that detects DNA lesions or replication blocks and coordinates various responses such as cell cycle arrests and transcriptional or posttranscriptional modifications. This mechanism is present in all eukaryotes and has been particularly analyzed in the yeast Saccharomyces cerevisiae, where it was originally identified (14, 53). In S. cerevisiae, activation of the DNA checkpoint by DNA lesions depends essentially on two sets of proteins, Rad24 and the PCNA-like trimer Rad17-Mec3-Ddc1, on the one hand, and the ATR homolog, the phosphatidylinositol 3-kinase-like Mec1 (in complex with an auxiliary subunit Ddc2), on the other hand (reviewed in references 28 and 58). Both the Rad17-Mec3-Ddc1 and the Mec1-Ddc2 complexes have been shown to be simultaneously and independently recruited to a double-strand break (DSB) artificially induced by the HO endonuclease (15,29). Once activated, Mec1 induces the phosphorylation and the activation of two central transducers, the Rad53 and Chk1 kinases, which subsequently phosphorylate downstream effectors. The phosphorylation of Rad53 and Chk1 also depends on so-called "adaptors," Rad9 in the case of DNA damage and Mrc1 in the case of replication blocks and DNA lesions during S phase (for a review on Rad53 activation, see reference 33).Rad53 plays a central part in S. cerevisiae DNA checkpoint: it controls the majority of the DNA damage responses and rad53⌬ cells are strongly hypersensitive to all genotoxic stresses. Rad53 is the founding member of the conserved family of FHA (forkhead associated) domain-containing checkpoint kinases, which also includes mammalian Chk2 and Schizosaccharomyces pombe Cds1. It contains two FHA domains, FHA1 and FHA2, flanking the protein catalytic domain. FHA domains are protein-protein interaction domains that specifica...

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Section: Ptc2 Threonine T376 Is Required For the Interaction Betweensupporting

confidence: 51%

Mechanisms of Checkpoint Kinase Rad53 Inactivation after a Double-Strand Break in Saccharomyces cerevisiae

Guillemain

Mauger

et al. 2007

Molecular and Cellular Biology

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“…Although Ptc2 and Ptc3 inhibit Hog1 similarly, they appear to act differently from Ptc1 in two respects (148). First, Ptc1 is required for maintaining basal Hog1 activity and dephosphorylating Hog1 during adaptation to stress, whereas Ptc2 and Ptc3 limit the maximum levels of Hog1 activity (140,148).…”

Section: Feedback Regulation Of the Hog Pathwaymentioning

confidence: 99%

Master and Commander in Fungal Pathogens: the Two-Component System and the HOG Signaling Pathway

2008

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“…However, these two phosphatases are also involved in the regulation of the Hog1 MAPK (Fig. 2a), but with a slightly different role than Ptc1, since in this case they serve to limit the maximum of activation of the HOG pathway after stress (114). Unlike Ptc1, Ptc2 and Ptc3 do not interact with Nbp2 (61).…”

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confidence: 99%

“…These two proteins differ structurally from Ptc1 because they possess a carboxyl-terminal extension of around 170 residues (Fig. 1) that, in the case of Ptc2, is necessary to achieve maximum activity (114). Ptc2 and Ptc3 are unable to fulfill the role of Ptc1 in the HOG pathway (57).…”

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confidence: 99%

Type 2C Protein Phosphatases in Fungi

2011

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Type 2C Ser/Thr phosphatases are a remarkable class of protein phosphatases, which are conserved in eukaryotes and involved in a large variety of functional processes. Unlike in other Ser/Thr phosphatases, the catalytic polypeptide is not usually associated with regulatory subunits, and functional specificity is achieved by encoding multiple isoforms. For fungi, most information comes from the study of type 2C protein phosphatase (PP2C) enzymes in Saccharomyces cerevisiae, where seven PP2C-encoding genes (PTC1 to -7) with diverse functions can be found. More recently, data on several Candida albicans PP2C proteins became available, suggesting that some of them can be involved in virulence. In this work we review the available literature on fungal PP2Cs and explore sequence databases to provide a comprehensive overview of these enzymes in fungi.Reversible phosphorylation of proteins is a major mechanism regulating many biological processes such as metabolism, gene transcription, or cell cycle. It is an extremely common event in signal transduction, and it is considered the main mechanism of posttranslational modification leading, for instance, to a change in enzyme activity. The phosphorylation state of a protein results from the balance of protein kinases and protein phosphatases activities. Alterations in the phosphorylation state of proteins are a cause of various diseases, such as cancer, diabetes, rheumatoid arthritis, or hypertension. The importance of this regulatory mechanism is evident when it is considered that it affects around 30% of the proteome of Saccharomyces cerevisiae (72) and that the number of genes encoding phosphatases and kinases represents 2 to 4% of all genes in a typical eukaryotic genome (60).Most phosphorylation events in eukaryotes involve transfer of phosphate to Ser and Thr residues. Removal of this phosphate is catalyzed by Ser/Thr protein phosphatases. Members of this large family of enzymes were initially classified, using enzymological criteria, as type 1 (PP1) and type 2 (PP2) phosphatases. PP2 enzymes were subsequently divided into three groups on the basis of the requirements for metal ions: 2A (not requiring metal ions), 2B (activated by calcium), and 2C (Mg 2ϩ dependent) (10). The molecular cloning of a number of cDNAs and genes from diverse organisms allowed the establishment of three major subfamilies: PPP (phosphoprotein phosphatases), including type 1, 2A, and 2B phosphatases, among others; PPM (metal-dependent protein phosphatases), including type 2C enzymes (PP2C), which are the subject of this review; and the catalytically Asp-based subfamily, represented by HAD and FCP/SCP (see reference 89 for a review).Although PP2C proteins are distantly related in primary sequence to PPP enzymes, their tridimensional structure and catalytic mechanisms appear to be quite similar. Type 2C phosphatases are widely represented in bacteria, fungi, plants, insects, and mammals (83), suggesting that they are involved in key cellular processes, such as proliferation, metabolism, and cell...

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Role of Ptc2 Type 2C Ser/Thr Phosphatase in Yeast High-Osmolarity Glycerol Pathway Inactivation

Cited by 76 publications

References 43 publications

Mechanisms of Checkpoint Kinase Rad53 Inactivation after a Double-Strand Break in Saccharomyces cerevisiae

Mechanisms of Checkpoint Kinase Rad53 Inactivation after a Double-Strand Break in Saccharomyces cerevisiae

Master and Commander in Fungal Pathogens: the Two-Component System and the HOG Signaling Pathway

Type 2C Protein Phosphatases in Fungi

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