Overexpression of OLE1 enhances stress tolerance and constitutively activates the MAPK HOG pathway in Saccharomyces cerevisiae.
OLE1 of Saccharomyces cerevisiae encodes the sole and essential Δ-9 desaturase catalyzing the conversion of saturated to unsaturated fatty acids. Upon ectopic overexpression of OLE1 in S. cerevisiae, significant increases in the membrane oleic acid content were observed. OLE1-overexpressing strains displayed enhanced tolerance to various stresses, better proton efflux, lower membrane permeability, and lessened internal hydrogen peroxide content. The OLE1-mediated enhanced stress tolerance was considerably diminished upon deletion of HOG1, which encodes the mitogen-activated protein kinase (MAPK) Hog1 of the high osmolarity glycerol (HOG) pathway. Furthermore, OLE1 overexpression constitutively activated Hog1, which remained in the cytoplasm. Hog1 activation was accomplished through the MAPK kinase kinase (MAPKKK) Ssk2, but not Ste11 and Ssk22, the other MAPKKKs of the HOG pathway. Despite its cytoplasmic location, activated Hog1 was able to activate the expression of its canonical targets, including CTT1, HSP12, and STL1, and further, the cAMP and stress response elements present in the promoter. OLE1 overexpression neither caused nor relieved endoplasmic reticulum stress. Individually or in combination, the physiological and molecular changes caused by OLE1 overexpression may contribute to enhanced tolerance to various types of stress. Biotechnol. Bioeng. 2017;114: 620-631. © 2016 Wiley Periodicals, Inc.
Interdisciplinary Program of EcoCreative, The Graduate School, Ewha Womans University, Seoul 03766, Korea.
Olviyani
O
Nasution
Department of Pharmacology, School of Medicine, Ajou University, Suwon, Korea.
Young Mi
YM
Lee
Department of Pharmacology, School of Medicine, Ajou University, Suwon, Korea.
Eunjung
E
Kim
Department of Life Sciences, College of Natural Sciences, Ewha Womans University, Seoul, Korea.
Yeji
Y
Lee
Department of Pharmacology, School of Medicine, Ajou University, Suwon, Korea.
Wankee
W
Kim
Interdisciplinary Program of EcoCreative, The Graduate School, Ewha Womans University, Seoul 03766, Korea.|Department of Life Sciences, College of Natural Sciences, Ewha Womans University, Seoul, Korea.
Wonja
W
Choi
D044943:Fatty Acid Desaturases / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D005227:Fatty Acids / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D009997:Osmotic Pressure / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013230:Stearoyl-CoA Desaturase; D015533:Transcriptional Activation / Q000235:genetics*
D005227:Fatty Acids; D029701:Saccharomyces cerevisiae Proteins; D044943:Fatty Acid Desaturases; D013230:Stearoyl-CoA Desaturase; C029627:delta-9 fatty acid desaturase; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae
Hog1 activation; Hog1 localization; OLE1 overexpression; gene activation; stress tolerance