GPD1, which encodes glycerol-3-phosphate dehydrogenase, is essential for growth under osmotic stress in Saccharomyces cerevisiae, and its expression is regulated by the high-osmolarity glycerol response pathway.

Abstract

The yeast Saccharomyces cerevisiae responds to osmotic stress, i.e., an increase in osmolarity of the growth medium, by enhanced production and intracellular accumulation of glycerol as a compatible solute. We have cloned a gene encoding the key enzyme of glycerol synthesis, the NADH-dependent cytosolic glycerol-3-phosphate dehydrogenase, and we named it GPD1. gpdlA mutants produced very little glycerol, and they were sensitive to osmotic stress. Thus, glycerol production is indeed essential for the growth of yeast cells during reduced water availability. hoglA mutants lacking a protein kinase involved in osmostress-induced signal transduction (the high-osmolarity glycerol response [HOG] pathway) failed to increase glycerol-3-phosphate dehydrogenase activity and mRNA levels when osmotic stress was imposed. Thus, expression of GPD1 is regulated through the HOG pathway. However, there may be Hogl-independent mechanisms mediating osmostress-induced glycerol accumulation, since a hoglA strain could still enhance its glycerol content, although less than the wild type. hoglA mutants are more sensitive to osmotic stress than isogenic gpdlA strains, and gpdlA hoglA double mutants are even more sensitive than either single mutant. Thus, the HOG pathway most probably has additional targets in the mechanism of adaptation to hypertonic medium.

Cloning, sequencing and characterization of a gene encoding dihydroxyacetone kinase from Zygosaccharomyces rouxii NRRL2547

“…This suggests that the upregulation of genes and enzymes involved in the DHA pathway when S. cerevisiae and Z. rouxii are grown under osmotic stress conditions (Van Zyl et al, 1991;Rep et al, 2000;Iwaki et al, 2001) might play an important role in the response of yeasts to osmotic stress. As previously reported (Albertyn et al, 1994), the intracellular glycerol concentration in S. cerevisiae increases significantly in response to hyperosmotic stress (Table 1). Similar intracellular glycerol levels were found in the three strains under hyperosmotic stress, whereas the level under nonosmostress conditions in the S. cerevisiae dak1 dak2 strain carrying the DAK1 gene of S. cerevisiae was significantly lower than in the other two strains, possibly due to the different vectors used (Table 1).…”

“…When the S. cerevisiae dak1 dak2 strain overexpressing the ZrDAK1 gene was cultivated under osmotic stress conditions (50 g/l NaCl), the generation time was 0.185/h, whereas in the absence of osmotic stress, the generation time was 0.180/h. This result was surprising, since the growth of S. cerevisiae grown on glucose is usually reduced significantly in the presence of 50 g/l NaCl (Albertyn et al, 1994). This suggests that the upregulation of genes and enzymes involved in the DHA pathway when S. cerevisiae and Z. rouxii are grown under osmotic stress conditions (Van Zyl et al, 1991;Rep et al, 2000;Iwaki et al, 2001) might play an important role in the response of yeasts to osmotic stress.…”

“…This is achieved by modulating the transport activity and by increased expression of GPD1 and GPP2 encoding glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase respectively (Albertyn et al, 1994;Norbeck et al, 1996). However, the expression of the DAK1 gene is also significantly induced by hyperosmotic stress in S. cerevisiae (Rep et al, 2000).…”

Inhibitory activity of blasticidin A, a strong aflatoxin production inhibitor, on protein synthesis of yeast: selective inhibition of aflatoxin production by protein synthesis inhibitors

“…Gpd1p is an enzyme required for glycerol synthesis and mRNA level of GPD1 is upregulated by high osmotic stress. 18 Phosphorylation of Cdc37p is important in the high osmotic stress signal transduction pathway that leads to glycerol synthesis. 19 Therefore, increase of levels of Gpd1p and phosphorylated Cdc37p by BcA treatment suggested that BcA might affect the high osmotic stress signal transduction pathway by increasing Cdc37p phosphorylation.…”

Regulatory network of genes associated with stimuli sensing, signal transduction and physiological transformation of appressorium inMagnaporthe oryzae

“…Glycerol-3-phosphate is further dephosphorylated to glycerol by glycerol-3-phosphatase, which includes two homologs encoded by HOR 1 and HOR 2 in S. cerevisiae (Hirayama et al 1995, Norbeck et al 1996). Gene replacement of the two homologous genes namely GPD 1 and GPD 2 resulted in mutants with a decreased accumulation of intracellular glycerol and increased sensitivity to osmotic stress as compared to wild-type in S. cerevisiae (Albertyn et al 1994). However, activities of GPD could not be detected during appressorium maturation, raising the possibility of an alternative glycerol production route needed to build up turgor pressure for appressorium penetration (Thines et al 2000a).…”