Using Lactococcus lactis for glutathione overproduction.
Glutathione and gamma-glutamylcysteine were produced in Lactococcus lactis using a controlled expression system and the genes gshA and gshB from Escherichia coli encoding the enzymes gamma-glutamylcysteine synthetase and glutathione synthetase. High levels of gamma-glutamylcysteine were found in strains growing on chemically defined medium and expressing either gshA alone or both gshA and gshB. As anticipated, glutathione was found in a strain expressing gshA and gshB. The level of glutathione production could be increased by addition of the precursor amino acid cysteine to the medium. The addition of cysteine led to an increased activity of glutathione synthetase, which is remarkable because the amino acid is not a substrate of this enzyme. The final intracellular glutathione concentration attained was 358 nmol mg(-1) protein, which is the highest concentration reported for a bacterium, demonstrating the suitability of engineered L. lactis for fine-chemical production and as a model for studies of the impact of glutathione on flavour formation and other properties of food.
Li
Yin
Y
Wageningen Centre for Food Sciences, NIZO food research, P.O. Box 20, 6710 Ede, The Netherlands.
Hugenholtz
Jeroen
J
Sybesma
Wilbert
W
Abee
Tjakko
T
Molenaar
Douwe
D
D003001:Cloning, Molecular; D003470:Culture Media / Q000737:chemistry; D003545:Cysteine / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry; D004151:Dipeptides / Q000096:biosynthesis; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005721:Glutamate-Cysteine Ligase / Q000235:genetics / Q000378:metabolism; D005978:Glutathione / Q000096:biosynthesis*; D005981:Glutathione Synthase / Q000235:genetics / Q000378:metabolism; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress
D003470:Culture Media; D004151:Dipeptides; D005721:Glutamate-Cysteine Ligase; D005981:Glutathione Synthase; D005978:Glutathione; D003545:Cysteine; C017341:gamma-glutamylcysteine