Primary structure of the gene encoding the bifunctional dihydrofolate reductase-thymidylate synthase of Leishmania major.
Primary structure of the gene encoding the bifunctional dihydrofolate reductase-thymidylate synthase of Leishmania major.
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DOI：
10.1073/pnas.83.8.2584
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发表时间：
1986-04
影响因子：
11.1
通讯作者：
S. Beverley;T. Ellenberger;J. S. Cordingley
中科院分区：
文献类型：
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作者：
S. Beverley;T. Ellenberger;J. S. Cordingley
测定了利什曼原虫二氢叶酸还原酶-胸腺苷酸合成酶（DHFR-TS）基因的核苷酸序列（二氢叶酸还原酶，EC 1.5.1.3和胸腺苷酸合成酶，EC 2.1.1.45）。DHFR-TS蛋白由基因组DNA中的单个1560碱基对开放阅读框编码，与脊椎动物dhfr或小鼠和噬菌体T4 TSs不同，后者含有中间序列。DHFR-TS序列与其他生物的DHFR和TS序列的比较表明，双功能多肽链内的酶活性顺序是DHFR后TS，利什曼双功能DHFR-TS独立进化而不是通过噬菌体t4相关的中间体，尽管双功能酶获得了新的功能特性，但DHFR和TS结构域的进化速度没有明显变化。利什曼原虫基因在第三个密码子位置上有86%的G+C，与寄生虫恶性疟原虫的基因相反，后者表现出相反的A+T倾向。DHFR-TS基因座编码在甲氨蝶呤耐药品系中扩增的DNA区域内，如前所述。
We have determined the nucleotide sequence of the dihydrofolate reductase-thymidylate synthetase (DHFR-TS) gene of the protozoan parasite Leishmania major (dihydrofolate reductase, EC 1.5.1.3 and thymidylate synthase, EC 2.1.1.45). The DHFR-TS protein is encoded by a single 1560-base-pair open reading frame within genomic DNA, in contrast to vertebrate DHFRs or mouse and phage T4 TSs, which contain intervening sequences. Comparisons of the DHFR-TS sequence with DHFR and TS sequences of other organisms indicate that the order of enzymatic activities within the bifunctional polypeptide chain is DHFR followed by TS, the Leishmania bifunctional DHFR-TS evolved independently and not through a phage T4-related intermediate, and the rate of evolution of both the DHFR and TS domains has not detectably changed despite the acquisition of new functional properties by the bifunctional enzyme. The Leishmania gene is 86% G+C in the third codon position, in contrast to genes of the parasite Plasmodium falciparum, which exhibit an opposite bias toward A+T. The DHFR-TS locus is encoded within a region of DNA amplified in methotrexate-resistant lines, as previously proposed.