Song J M, Rabinowitz J C
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
FEBS Lett. 1995 Dec 4;376(3):229-32. doi: 10.1016/0014-5793(95)01288-9.
The yeast ADE3(1-333) gene which encodes a truncated protein containing the N-terminal 5,10-methylene-tetrahydrofolate (THF) dehydrogenase (D)/5,10-methyl-THF cyclohydrolase (C) domain of cytoplasmic trifunctional C1-THF synthase is able to complement all the phenotypes associated with ade3 mutations in vivo. However, expression of the ADE3(1-333) gene in an ade3 strain does not retain any D activity in vitro. Expression in a yeast ade3 strain of the ADE3(1-333) fused to the Escherichia coli lacZ gene or to the yeast SER2 gene allows detection of D and C activities in vitro. These results indicate that the N-terminal D/C domain of C1-THF synthase requires the C-terminal 10-formyl-THF synthetase domain for stable catalytic activity in vitro.
酵母ADE3(1 - 333)基因编码一种截短蛋白，该蛋白包含细胞质三功能C1 - 四氢叶酸（THF）合酶的N端5,10 - 亚甲基 - 四氢叶酸脱氢酶（D）/5,10 - 甲基 - THF环水解酶（C）结构域，能够在体内互补与ade3突变相关的所有表型。然而，在ade3菌株中表达ADE3(1 - 333)基因在体外并不保留任何D活性。将ADE3(1 - 333)与大肠杆菌lacZ基因或酵母SER2基因融合后在酵母ade3菌株中表达，可在体外检测到D和C活性。这些结果表明，C1 - THF合酶的N端D/C结构域在体外需要C端10 - 甲酰 - THF合成酶结构域来实现稳定的催化活性。
