Nardese V, Gütlich M, Brambilla A, Carbone M L
Dipartimento di Genetica e di Biologia dei Microrganismi, Università di Milano, Italy.
Biochem Biophys Res Commun. 1996 Jan 5;218(1):273-9. doi: 10.1006/bbrc.1996.0048.
GTP-cyclohydrolase I is the first enzyme in the biosynthetic pathway leading to folic acid and tetrahydrobiopterin. We determined the complete sequence of the GTP-cyclohydrolase I gene from the yeast Saccharomyces cerevisiae. The gene, which is located in the subtelomeric region of the right arm of chromosome VII, gives a major transcript of about 1000 nt and encodes a protein of 243 amino acids, which is highly homologous to the GTP-cyclohydrolase I from bacteria to man. We obtained by gene replacement a knock-out mutant that shows a recessive conditional lethality due to folinic acid auxotrophy, and lacks any detectable specific enzymatic activity. The gene was identified as FOL2, previously genetically mapped in the same region (J. Game, personal communication).
GTP环化水解酶I是叶酸和四氢生物蝶呤生物合成途径中的首个酶。我们测定了来自酿酒酵母的GTP环化水解酶I基因的完整序列。该基因位于染色体VII右臂的亚端粒区域，产生一个约1000 nt的主要转录本，编码一种由243个氨基酸组成的蛋白质，该蛋白质与从细菌到人类的GTP环化水解酶I高度同源。我们通过基因替换获得了一个敲除突变体，该突变体由于亚叶酸营养缺陷而表现出隐性条件致死性，并且缺乏任何可检测到的特异性酶活性。该基因被鉴定为FOL2，之前已在同一区域进行了遗传定位（J. Game，个人交流）。
