title: Hexavalent chromium stimulation of riboflavin synthesis in flavinogenic yeast.
abstract: Flavinogenic yeast overproduce riboflavin (RF) in iron-deprived media. In optimal growth media supplemented with Fe, hexavalent chromium 'Cr (VI)' treatment led to elevated RF synthesis in all cases of 37 flavinogenic strains studied. The level of RF production exceeded the rate observed at iron-deficient conditions. At sublethal Cr concentrations the RF oversynthesis over time correlated well with the growth-inhibitory adaptational period as manifested by the prolonged lag phase. The consecutive logarithmic biomass growth was accompanied by a drop in RF biosynthesis. Cr (VI)-induced RF overproduction was not a result of cellular iron level decrease. The treatment of yeast with Cr (VI) led to the stimulation of GTP-cyclohydrolase and RF-synthase activities, the key enzymes of the RF biosynthesis pathway.
authors.affiliation: Division of Regulatory Cell Systems, A. V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Lviv.
authors.forename: D
authors.initials: D
authors.lastname: Fedorovych
authors.forename: H
authors.initials: H
authors.lastname: Kszeminska
authors.forename: L
authors.initials: L
authors.lastname: Babjak
authors.forename: P
authors.initials: P
authors.lastname: Kaszycki
authors.forename: H
authors.initials: H
authors.lastname: Koloczek
mesh_terms: D002412:Cations / Q000633:toxicity; D002455:Cell Division / Q000187:drug effects; D002857:Chromium / Q000633:toxicity*; D003470:Culture Media; D006136:GTP Cyclohydrolase / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D012256:Riboflavin / Q000096:biosynthesis*; D012258:Riboflavin Synthase / Q000378:metabolism; D015003:Yeasts / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D002412:Cations; D003470:Culture Media; D002857:Chromium; D007501:Iron; D012258:Riboflavin Synthase; D006136:GTP Cyclohydrolase; D012256:Riboflavin