Logvinenko E M, Shavlovskiĭ G M, Kontorovskaia N Iu
Genetika. 1987 Sep;23(9):1699-701.
The biosynthesis of riboflavin precursor 6,7-dimethyl-8-ribityllumazine was studied in extracts of Pichia guilliermondii yeast mutants of rib5 and rib6 genotypes with impaired synthesis of proteins P1 and P2, respectively. It was shown that synthesis of 6,7-dimethyl-8-ribityllumazine took place in extracts of rib5 mutant (active P1 protein) in the presence of 2,4-dihydroxy-5-amino-6-ribitylaminopyrimidine and the compound formed from ribose-5-phosphate by extracts of rib6 mutant (active P2 protein). No lumazine was formed in extracts of rib6 mutant from pyrimidine substrate and ribose-5-phosphate preincubated with extracts of rib5 mutant. Hence, P1 protein (the product of RIB5 gene) participates in the biosynthesis of 6,7-dimethyl-8-ribityllumazine from 2,4-dihydroxy-5-amino-6-ribitylaminopyrimidine and aliphatic intermediate which is formed from ribose-5-phosphate, under the action of P2 protein (the product of RIB6 gene).
在分别缺失P1和P2蛋白合成功能的季也蒙毕赤酵母rib5和rib6基因型酵母突变体提取物中，对核黄素前体6,7-二甲基-8-核糖基卢马嗪的生物合成进行了研究。结果表明，在2,4-二羟基-5-氨基-6-核糖基氨基嘧啶和由rib6突变体提取物（活性P2蛋白）从5-磷酸核糖形成的化合物存在的情况下，rib5突变体提取物（活性P1蛋白）中发生了6,7-二甲基-8-核糖基卢马嗪的合成。用rib5突变体提取物预孵育的嘧啶底物和5-磷酸核糖在rib6突变体提取物中未形成卢马嗪。因此，P1蛋白（RIB5基因的产物）在P2蛋白（RIB6基因的产物）的作用下，参与了由2,4-二羟基-5-氨基-6-核糖基氨基嘧啶和由5-磷酸核糖形成的脂肪族中间体合成6,7-二甲基-8-核糖基卢马嗪的过程。
