Effects of deletion of different PP2C protein phosphatase genes on stress responses inSaccharomyces cerevisiae

Abstract

A key mechanism of signal transduction in eukaryotes is reversible protein phosphorylation, mediated through protein kinases and protein phosphatases (PPases). Modulation of signal transduction by this means regulates many biological processes. Saccharomyces cerevisiae has 40 PPases, including seven protein phosphatase 2C (PP2C PPase) genes (PTC1-PTC7). However, their precise functions remain poorly understood. To elucidate their cellular functions and to identify those that are redundant, we constructed 127 strains with deletions of all possible combinations of the seven PP2C PPase genes. All 127 disruptants were viable under nutrient-rich conditions, demonstrating that none of the combinations induced synthetic lethality under these conditions. However, several combinations exhibited novel phenotypes, e.g. the Δptc5Δptc7 double disruptant and the Δptc2Δptc3Δptc5Δptc7 quadruple disruptant exhibited low (13°C) and high (37°C) temperature-sensitive growth, respectively. Interestingly, the septuple disruptant Δptc1Δptc2Δptc3Δptc4Δptc5Δptc6Δptc7 showed an essentially normal growth phenotype at 37°C. The Δptc2Δptc3Δptc5Δptc7 quadruple disruptant was sensitive to LiCl (0.4 M). Two double disruptants, Δptc1Δptc2 and Δptc1Δptc4, displayed slow growth and Δptc1Δptc2Δptc4 could not grow on medium containing 1.5 M NaCl. The Δptc1Δptc6 double disruptant showed increased sensitivity to caffeine, congo red and calcofluor white compared to each single deletion. Our observations indicate that S. cerevisiae PP2C PPases have a shared and important role in responses to environmental stresses. These disruptants also provide a means for exploring the molecular mechanisms of redundant PTC gene functions under defined conditions.

Differential proteomic analysis by SWATH-MS unravels the most dominant mechanisms underlying yeast adaptation to non-optimal temperatures under anaerobic conditions

“…Another interesting feature is the downregulation of Ptc2 in the CEN.PK strain compared to ADY5, a phosphatase protein known to negatively regulate the high-osmolarity glycerol (HOG) pathway, along with Ptc1 and Ptc3 66 . The HOG pathway is a preserved MAPK cascade in S. cerevisiae, which among other functions, is critical for tolerance to different stresses, such as osmotic, citric acid stress and heat stress 67 . Additionally, Panadero et al (2005) showed that the HOG pathway is clearly activated in response to a downshift in temperature from 30 °C to 12 °C, participating in the transmission of the cold signal and on the regulation of the expression of a subset of cold-induced genes 68 .…”

“…Additionally, Panadero et al (2005) showed that the HOG pathway is clearly activated in response to a downshift in temperature from 30 °C to 12 °C, participating in the transmission of the cold signal and on the regulation of the expression of a subset of cold-induced genes 70 . So, the downregulation of Ptc2, which directly dephosphorylates Hog1 MAPK and limits the maximal activation of the HOG pathway 69 , may be related to this need to activate this pathway.…”

Wide-Ranging Effects of the Yeast Ptc1 Protein Phosphatase Acting Through the MAPK Kinase Mkk1

“…Phosphorylation of Slt2 occurs at Tyr and Thr residues in a T-X-Y motif within the activation loop common to MAPKs [see Levin (2011) for a review]. In keeping with the involvement of Ptc1 in the CWI pathway, ptc1 mutants are sensitive to diverse cell-wall antagonists such as calcofluor white (CFW), Congo red, caffeine, and caspofungin (Ram et al 1994;Markovich et al 2004;Sharmin et al 2014) or to other conditions that activate the CWI pathway, such as alkaline pH . In addition, the ptc1 mutation is synthetically lethal with mutations in genes that are important for cell-wall construction, such as FKS1, GAS1, and SMI1 ( Lesage et al 2004).…”

TheSaccharomyces cerevisiaePtc1 protein phosphatase attenuates G2‐M cell cycle blockage caused by activation of the cell wall integrity pathway

“…It is remarkable that, though the type 2C phosphatase family is composed of six additional members (Ptc2 to Ptc7) we never recovered a PTC gene as ptc1 suppressor. This reinforces the notion that most biological properties of Ptc1 are not shared by other members of the gene family (Gonzalez et al ., ; Gonzalez et al ., ; Sharmin et al ., ). Although several of the suppressor genes were able to alleviate many ptc1 related phenotypes (i.e.…”