title: Extracellular glutathione fermentation using engineered Saccharomyces cerevisiae expressing a novel glutathione exporter.
abstract: A novel extracellular glutathione fermentation method using engineered Saccharomyces cerevisiae was developed by following three steps. First, a platform host strain lacking the glutathione degradation protein and glutathione uptake protein was constructed. This strain improved the extracellular glutathione productivity by up to 3.2-fold compared to the parental strain. Second, the ATP-dependent permease Adp1 was identified as a novel glutathione export ABC protein (Gxa1) in S. cerevisiae based on the homology of the protein sequence with that of the known human glutathione export ABC protein (ABCG2). Overexpression of this GXA1 gene improved the extracellular glutathione production by up to 2.3-fold compared to the platform host strain. Finally, combinatorial overexpression of the GXA1 gene and the genes involved in glutathione synthesis in the platform host strain increased the extracellular glutathione production by up to 17.1-fold compared to the parental strain. Overall, the metabolic engineering of the glutathione synthesis, degradation, and transport increased the total (extracellular + intracellular) glutathione production. The extracellular glutathione fermentation method developed in this study has the potential to overcome the limitations of the present intracellular glutathione fermentation process in yeast.
authors.affiliation: Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Kiriyama
authors.forename: Kiyotaka Y
authors.initials: KY
authors.lastname: Hara
authors.forename: Akihiko
authors.initials: A
authors.lastname: Kondo
mesh_terms: D005285:Fermentation; D015966:Gene Expression Regulation, Fungal; D005978:Glutathione / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000235:genetics* / Q000378:metabolism; D060847:Metabolic Engineering; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C073030:ADP1 protein, S cerevisiae; D026901:Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D005978:Glutathione