Fling M E, Kopf J, Richards C A
Wellcome Research Laboratories, Research Triangle Park, NC 27709.
Gene. 1988 Mar 31;63(2):165-74. doi: 10.1016/0378-1119(88)90522-7.
The nucleotide sequence of a DNA fragment that contained the Saccharomyces cerevisiae gene DFR coding for dihydrofolate reductase (DHFR) was determined. The DHFR was encoded by a 633-bp open reading frame, which specified an Mr24264 protein. The polypeptide was significantly related to the DHFRs of chicken liver and Escherichia coli. The yeast enzyme shared 60 amino acid (aa) residues with the avian enzyme and 51 aa residues with the bacterial enzyme. DHFR was overproduced about 40-fold in S. cerevisiae when the cloned gene was present in the vector YEp24. As isolated from the Saccharomyces library, the DFR gene was not expressed in E. coli. When the gene was present on a 1.8-kb BamHI-SalI fragment subcloned into the E. coli vector, pUC18, weak expression in E. coli was observed.
测定了包含编码二氢叶酸还原酶（DHFR）的酿酒酵母基因DFR的DNA片段的核苷酸序列。DHFR由一个633bp的开放阅读框编码，该开放阅读框指定了一个Mr24264的蛋白质。该多肽与鸡肝和大肠杆菌的DHFR有显著相关性。酵母酶与禽类酶共有60个氨基酸残基，与细菌酶共有51个氨基酸残基。当克隆基因存在于载体YEp24中时，DHFR在酿酒酵母中的产量提高了约40倍。从酿酒酵母文库中分离得到的DFR基因在大肠杆菌中不表达。当该基因存在于亚克隆到大肠杆菌载体pUC18中的1.8kb BamHI-SalI片段上时，在大肠杆菌中观察到了微弱的表达。
