title: Enhancing the flux of D-glucose to the pentose phosphate pathway in Saccharomyces cerevisiae for the production of D-ribose and ribitol.
abstract: Phosphoglucose isomerase-deficient (pgi1) strains of Saccharomyces cerevisiae were studied for the production of D-ribose and ribitol from D-glucose via the intermediates of the pentose phosphate pathway. Overexpression of the genes coding for NAD(+)-specific glutamate dehydrogenase (GDH2) of S. cerevisiae or NADPH-utilising glyceraldehyde-3-phosphate dehydrogenase (gapB) of Bacillus subtilis enabled growth of the pgi1 mutant strains on D-glucose. Overexpression of the gene encoding sugar phosphate phosphatase (DOG1) of S. cerevisiae was needed for the production of D-ribose and ribitol; however, it reduced the growth of the pgi1 strains expressing GDH2 or gapB in the presence of higher D-glucose concentrations. The CEN.PK2-1D laboratory strain expressing both gapB and DOG1 produced approximately 0.4 g l(-1) of D-ribose and ribitol when grown on 20 g l(-1) (w/v) D-fructose with 4 g l(-1) (w/v) D-glucose. Nuclear magnetic resonance measurements of the cells grown with (13)C-labelled D-glucose showed that about 60% of the D-ribose produced was derived from D-glucose. Strains deficient in both phosphoglucose isomerase and transketolase activities, and expressing DOG1 and GDH2 tolerated only low D-glucose concentrations (< or =2 g l(-1) (w/v)), but produced 1 g l(-1) (w/v) D-ribose and ribitol when grown on 20 g l(-1) (w/v) D-fructose with 2 g l(-1) (w/v) D-glucose.
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland. Mervi.Toivari@vtt.fi
authors.forename: Mervi H
authors.initials: MH
authors.lastname: Toivari
authors.forename: Hannu
authors.initials: H
authors.lastname: Maaheimo
authors.forename: Merja
authors.initials: M
authors.lastname: Penttilä
authors.forename: Laura
authors.initials: L
authors.lastname: Ruohonen
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000235:genetics; D002250:Carbon Radioisotopes / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000172:deficiency; D018628:Gene Dosage; D015870:Gene Expression; D005818:Genetic Engineering; D005947:Glucose / Q000378:metabolism*; D005969:Glutamate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating) / Q000235:genetics / Q000378:metabolism; D019746:Intramolecular Oxidoreductases / Q000172:deficiency; D009682:Magnetic Resonance Spectroscopy; D053858:Metabolic Networks and Pathways / Q000235:genetics*; D010427:Pentose Phosphate Pathway; D012255:Ribitol / Q000378:metabolism*; D012266:Ribose / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D013194:Staining and Labeling / Q000379:methods
chemical_list: D002250:Carbon Radioisotopes; D029701:Saccharomyces cerevisiae Proteins; D012255:Ribitol; D012266:Ribose; D003577:Cytochrome P-450 Enzyme System; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating); D005969:Glutamate Dehydrogenase; C061421:glutamate dehydrogenase (NAD(P)+); D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase; D005947:Glucose