The role of the Snf1 kinase in the adaptive response of Saccharomyces cerevisiae to alkaline pH stress

2012 ◽  
Vol 444 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Antonio Casamayor ◽  
Raquel Serrano ◽  
María Platara ◽  
Carlos Casado ◽  
Amparo Ruiz ◽  
...  

Alkaline pH stress invokes a potent and fast transcriptional response in Saccharomyces cerevisiae that includes many genes repressed by glucose. Certain mutants in the glucose-sensing and -response pathways, such as those lacking the Snf1 kinase, are sensitive to alkalinization. In the present study we show that the addition of glucose to the medium improves the growth of wild-type cells at high pH, fully abolishes the snf1 alkali-sensitive phenotype and attenuates high pH-induced Snf1 phosphorylation at Thr210. Lack of Elm1, one of the three upstream Snf1 kinases (Tos3, Elm1 and Sak1), markedly increases alkali sensitivity, whereas the phenotype of the triple mutant tos3 elm1 sak1 is even more pronounced than that of snf1 cells and is poorly rescued by glucose supplementation. DNA microarray analysis reveals that about 75% of the genes induced in the short term by high pH are also induced by glucose scarcity. Snf1 mediates, in full or in part, the activation of a significant subset (38%) of short-term alkali-induced genes, including those encoding high-affinity hexose transporters and phosphorylating enzymes. The induction of genes encoding enzymes involved in glycogen, but not trehalose, metabolism is largely dependent of the presence of Snf1. Therefore the function of Snf1 in adaptation to glucose scarcity appears crucial for alkaline pH tolerance. Incorporation of micromolar amounts of iron and copper to a glucose-supplemented medium resulted in an additive effect and allows near-normal growth at high pH, thus indicating that these three nutrients are key limiting factors for growth in an alkaline environment.

2006 ◽  
Vol 281 (52) ◽  
pp. 39785-39795 ◽  
Author(s):  
Raquel Serrano ◽  
Humberto Martín ◽  
Antonio Casamayor ◽  
Joaquín Ariño

2015 ◽  
Vol 2 (6) ◽  
pp. 182-196 ◽  
Author(s):  
Albert Serra-Cardona ◽  
David Canadell ◽  
Joaquin Arino

2021 ◽  
Vol 7 (7) ◽  
pp. 527
Author(s):  
Lisa Wasserstrom ◽  
Jürgen Wendland

Microorganisms need to sense and adapt to fluctuations in the environmental pH. In fungal species, this response is mediated by the conserved pacC/RIM101 pathway. In Aspergillus nidulans, PacC activates alkaline-expressed genes and represses acid-controlled genes in response to alkaline pH and has important functions in regulating growth and conidia formation. In Saccharomyces cerevisiae, the PacC homolog Rim101 is required for adaptation to extracellular pH and to regulate transcription of IME1, the Initiator of MEiosis. S. cerevisiae rim101 mutants are defective in sporulation. In Ashbya gossypii, a filamentous fungus belonging to the family of Saccharomycetaceae, little is known about the role of pH in regulating growth and sporulation. Here, we deleted the AgRIM101 homolog (AFR190C). Our analyses show that Rim101 is important for growth and essential for sporulation at alkaline pH in A. gossypii. Acidic liquid sporulation media were alkalinized by sporulating strains, while the high pH of alkaline media (starting pH = 8.6) was reduced to a pH ~ 7.5 by these strains. However, Agrim101 mutants were unable to sporulate in alkaline media and failed to reduce the initial high pH, while they were capable of sporulation in acidic liquid media in which they increased the pH like the wild type.


2007 ◽  
Vol 7 (2) ◽  
pp. 286-293 ◽  
Author(s):  
Sam Van de Velde ◽  
Johan M. Thevelein

ABSTRACT Under specific environmental conditions, the yeast Saccharomyces cerevisiae can undergo a morphological switch to a pseudohyphal growth pattern. Pseudohyphal differentiation is generally studied upon induction by nitrogen limitation in the presence of glucose. It is known to be controlled by several signaling pathways, including mitogen-activated protein kinase, cyclic AMP-protein kinase A (cAMP-PKA), and Snf1 kinase pathways. We show that the alpha-glucoside sugars maltose and maltotriose, and especially sucrose, are more potent inducers of filamentation than glucose. Sucrose even induces filamentation in nitrogen-rich media and in the mep2Δ/mep2Δ ammonium permease mutant on ammonium-limiting medium. We demonstrate that glucose also inhibits filamentation by means of a pathway parallel to the cAMP-PKA pathway. Deletion of HXK2 shifted the pseudohyphal growth pattern on glucose to that of sucrose, while deletion of SNF4 abrogated filamentation on both sugars, indicating a negative role of glucose repression and a positive role for Snf1 activity in the control of filamentation. In all strains and in all media, sucrose induction of filamentation is greatly diminished by deletion of the sucrose/glucose-sensing G-protein-coupled receptor Gpr1, whereas it has no effect on induction by maltose and maltotriose. The competence of alpha-glucoside sugars to induce filamentation is reflected in the increased expression of the cell surface flocculin gene FLO11. In addition, sucrose is the only alpha-glucoside sugar capable of rapidly inducing FLO11 expression in a Gpr1-dependent manner, reflecting the sensitivity of Gpr1 for this sugar and its involvement in rapid sucrose signaling. Our study identifies sucrose as the most potent nutrient inducer of pseudohyphal growth and shows that glucose inactivation of Snf1 kinase signaling is responsible for the lower potency of glucose.


Genetics ◽  
1993 ◽  
Vol 135 (2) ◽  
pp. 321-326 ◽  
Author(s):  
H Mitsuzawa

Abstract The Saccharomyces cerevisiae strain P-28-24C, from which cAMP requiring mutants derived, responded to exogenously added cAMP. Upon the addition of cAMP, this strain showed phenotypes shared by mutants with elevated activity of the cAMP pathway. Genetic analysis involving serial crosses of this strain to a strain with another genetic background revealed that the responsiveness to cAMP results from naturally occurring loss-of-function alleles of PDE1 and PDE2, which encode low and high affinity cAMP phosphodiesterases, respectively. In addition, P-28-24C was found to carry a mutation conferring slow growth that lies in CYR1, which encodes adenylate cyclase, and the slow growth phenotype caused by the cyr1 mutation was suppressed by the pde2 mutation. Therefore P-28-24C is fortuitously a pde1 pde2 cyr1 triple mutant. Responsiveness to cAMP conferred by pde mutations suggests that S. cerevisiae cells are permeable to cAMP to some extent and that the apparent absence of effect of exogenously added cAMP on wild-type cells is due to immediate degradation by cAMP phosphodiesterases.


Author(s):  
Hamid Niazi ◽  
Shidong Wang ◽  
Lyndon Lamborn ◽  
Reg Eadie ◽  
Weixing Chen ◽  
...  

Genetics ◽  
2001 ◽  
Vol 158 (2) ◽  
pp. 563-572 ◽  
Author(s):  
Valmik K Vyas ◽  
Sergei Kuchin ◽  
Marian Carlson

Abstract The Snf1 protein kinase is essential for the transcription of glucose-repressed genes in Saccharomyces cerevisiae. We identified Nrg2 as a protein that interacts with Snf1 in the two-hybrid system. Nrg2 is a C2H2 zinc-finger protein that is homologous to Nrg1, a repressor of the glucose- and Snf1-regulated STA1 (glucoamylase) gene. Snf1 also interacts with Nrg1 in the two-hybrid system and co-immunoprecipitates with both Nrg1 and Nrg2 from cell extracts. A LexA fusion to Nrg2 represses transcription from a promoter containing LexA binding sites, indicating that Nrg2 also functions as a repressor. An Nrg1 fusion to green fluorescent protein is localized to the nucleus, and this localization is not regulated by carbon source. Finally, we show that VP16 fusions to Nrg1 and Nrg2 allow low-level expression of SUC2 in glucose-grown cells, and we present evidence that Nrg1 and Nrg2 contribute to glucose repression of the DOG2 gene. These results suggest that Nrg1 and Nrg2 are direct or indirect targets of the Snf1 kinase and function in glucose repression of a subset of Snf1-regulated genes.


Sign in / Sign up

Export Citation Format

Share Document