Fedorovych D, Kszeminska H, Babjak L, Kaszycki P, Koloczek H
Division of Regulatory Cell Systems, A. V. Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Lviv.
Biometals. 2001 Mar;14(1):23-31. doi: 10.1023/a:1016643307690.
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.
产黄素酵母在缺铁培养基中过量生产核黄素（RF）。在添加了铁的最佳生长培养基中，六价铬“Cr（VI）”处理导致在所研究的37株产黄素菌株的所有情况下，RF合成均升高。RF的产量水平超过了在缺铁条件下观察到的速率。在亚致死Cr浓度下，随着时间的推移，RF的过量合成与生长抑制适应期密切相关，表现为延迟期延长。随后的对数期生物量增长伴随着RF生物合成的下降。Cr（VI）诱导的RF过量生产不是细胞铁水平降低的结果。用Cr（VI）处理酵母会刺激GTP-环水解酶和RF合成酶的活性，这两种酶是RF生物合成途径的关键酶。
