title: Altered expression and activities of enzymes involved in thiamine diphosphate biosynthesis in Saccharomyces cerevisiae under oxidative and osmotic stress.
abstract: Thiamine diphosphate (TDP) serves as a cofactor for enzymes engaged in pivotal carbohydrate metabolic pathways, which are known to be modulated under stress conditions to ensure the cell survival. Recent reports have proven a protective role of thiamine (vitamin B(1)) in the response of plants to abiotic stress. This work aimed at verifying a hypothesis that also baker's yeast, which can synthesize thiamine de novo similarly to plants and bacteria, adjust thiamine metabolism to adverse environmental conditions. Our analyses on the gene expression and enzymatic activity levels generally showed an increased production of thiamine biosynthesis enzymes (THI4 and THI6/THI6), a TDP synthesizing enzyme (THI80/THI80) and a TDP-requiring enzyme, transketolase (TKL1/TKL) by yeast subjected to oxidative (1 mM hydrogen peroxide) and osmotic (1 M sorbitol) stress. However, these effects differed in magnitude, depending on yeast growth phase and presence of thiamine in growth medium. A mutant thi4Δ with increased sensitivity to oxidative stress exhibited enhanced TDP biosynthesis as compared with the wild-type strain. Similar tendencies were observed in mutants yap1Δ and hog1Δ defective in the signaling pathways of the defense against oxidative and osmotic stress, respectively, suggesting that thiamine metabolism can partly compensate damages of yeast general defense systems.
authors.affiliation: Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland. ewa.b.kowalska@uj.edu.pl
authors.forename: Ewa
authors.initials: E
authors.lastname: Kowalska
authors.forename: Marta
authors.initials: M
authors.lastname: Kujda
authors.forename: Natalia
authors.initials: N
authors.lastname: Wolak
authors.forename: Andrzej
authors.initials: A
authors.lastname: Kozik
mesh_terms: D053898:Biosynthetic Pathways / Q000235:genetics*; D004798:Enzymes / Q000096:biosynthesis; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D009997:Osmotic Pressure; D018384:Oxidative Stress; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis; D013835:Thiamine Pyrophosphate / Q000096:biosynthesis*
chemical_list: D004798:Enzymes; D029701:Saccharomyces cerevisiae Proteins; D013835:Thiamine Pyrophosphate