Role of Hog1, Tps1 and Sod1 in boric acid tolerance of Saccharomyces cerevisiae.
In order to identify genetic contributions to boric acid (BA) resistance, a yeast knockout collection was screened for BA-sensitive mutants. Prominent among the BA-sensitive mutants were strains with defects in the cytoplasmic part of the high osmolarity/glycerol (HOG) signalling pathway, the trehalose-synthesis pathway (TPS1/TPS2) and the copper-zinc superoxide dismutase SOD1. An analysis of HOG-pathway mutants and fluorescence microscopy of Hog1-GFP fusions showed that the non-redundant cytoplasmic components of the pathway, Pbs2p and Hog1p, are required to maintain BA resistance, but that import of the activated Hog1p kinase into the nucleus neither occurs during BA stress nor is necessary for wild-type-like BA tolerance. Pbs2p and Hog1p are also required to support normal morphogenesis during BA stress as their absence leads to BA-induced hyperpolarized growth. An analysis of Sod1p and Tps1p expression revealed that BA stress induces superoxide dismutase and increases trehalose synthesis activity, albeit only after a 7 h delay. We conclude that normal BA resistance of Saccharomyces cerevisiae depends on the functioning of HOG signalling, the trehalose synthesis pathway and superoxide dismutase activity.
Des Moines University, 3200 Grand Avenue, Des Moines, IA 50312, USA.
Martin
M
Schmidt
Des Moines University, 3200 Grand Avenue, Des Moines, IA 50312, USA.
Kento
K
Akasaka
Des Moines University, 3200 Grand Avenue, Des Moines, IA 50312, USA.
Jeffrey T
JT
Messerly
Des Moines University, 3200 Grand Avenue, Des Moines, IA 50312, USA.
Michael P
MP
Boyer
D001888:Boric Acids / Q000494:pharmacology*; D025141:Drug Resistance, Fungal; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D009994:Osmolar Concentration; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism*; D000072105:Superoxide Dismutase-1; D014199:Trehalose / Q000378:metabolism
D001888:Boric Acids; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D014199:Trehalose; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases; D005990:Glycerol; C032688:boric acid