title: Preparation of a γ-glutamylcysteine-enriched yeast extract from a newly developed GSH2-deficient strain.
abstract: Gamma-glutamylcysteine (γ-GC), the precursor of glutathione (GSH), may have significant health benefits as a dietary supplement, but there are few cost-effective methods available for its large-scale production. We developed an efficient method for producing γ-GC in a mutant yeast strain using a three-step breeding procedure and a unique cultivation process. In the first breeding step, we prepared a glutathione synthetase (GSH2)-deficient yeast mutant. In the second step, selenate (SeO(4)(2-)) sensitivity was introduced by crossing the GSH2-deficient mutant with a strain harboring the met30 mutation. In the final step, pantothenic acid auxotrophy was introduced by ethyl methanesulfonate mutagenesis. The isolated strain displayed significantly enhanced cellular γ-GC when cultivated in synthetic medium without pantothenic acid, reaching a maximum level of 4.39% of dry cell weight. Using this strain, we were able to prepare a yeast extract containing approximately 13% γ-GC (w/w), which is markedly higher than the reported value (0.3%) of commercially available yeast extracts. The present method may facilitate large-scale γ-GC production for investigating the nutritive value and other benefits of dietary γ-GC.
authors.affiliation: Ajinomoto Co., Inc., 1-1 Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa 210-8681, Japan. hiroaki_nishiuchi@ajinomoto.com
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishiuchi
authors.forename: Mariko
authors.initials: M
authors.lastname: Suehiro
authors.forename: Reiko
authors.initials: R
authors.lastname: Sugimoto
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamagishi
mesh_terms: D002458:Cell Fractionation; D005591:Chemical Fractionation; D003470:Culture Media / Q000737:chemistry; D004151:Dipeptides / Q000032:analysis* / Q000096:biosynthesis*; D044783:F-Box Proteins / Q000235:genetics; D055951:Functional Food / Q000600:supply & distribution; D005978:Glutathione / Q000032:analysis / Q000172:deficiency; D005981:Glutathione Synthase / Q000172:deficiency* / Q000235:genetics; D009154:Mutation / Q000235:genetics; D010205:Pantothenic Acid / Q000172:deficiency; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D064586:Selenic Acid / Q000494:pharmacology; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics
chemical_list: D003470:Culture Media; D004151:Dipeptides; D044783:F-Box Proteins; C470285:MET30 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D010205:Pantothenic Acid; D043743:Ubiquitin-Protein Ligase Complexes; D005981:Glutathione Synthase; D005978:Glutathione; D064586:Selenic Acid; C017341:gamma-glutamylcysteine