CLONING OF A CHICKEN LIVER CDNA-ENCODING 5-AMINOIMIDAZOLE RIBONUCLEOTIDE CARBOXYLASE AND 5-AMINOIMIDAZOLE-4-N-SUCCINOCARBOXAMIDE RIBONUCLEOTIDE SYNTHETASE BY FUNCTIONAL COMPLEMENTATION OF ESCHERICHIA-COLI PUR MUTANTS
CLONING OF A CHICKEN LIVER CDNA-ENCODING 5-AMINOIMIDAZOLE RIBONUCLEOTIDE CARBOXYLASE AND 5-AMINOIMIDAZOLE-4-N-SUCCINOCARBOXAMIDE RIBONUCLEOTIDE SYNTHETASE BY FUNCTIONAL COMPLEMENTATION OF ESCHERICHIA-COLI PUR MUTANTS
复制标题
DOI：
10.1073/pnas.87.8.3097
复制
发表时间：
1990-04-01
影响因子：
11.1
通讯作者：
ZALKIN, H
中科院分区：
文献类型：
--
作者：
CHEN, ZD;DIXON, JE;ZALKIN, H
我们利用大肠杆菌pur突变体的功能互补，克隆了禽类编码5-氨基咪唑核糖核苷酸(AIR)carboxylase-5-aminoimidazole-4-N-succinocarboxamide核糖核苷酸合成酶(SAICAR)的基因，该双功能酶催化从头合成嘌呤核苷酸途径中的步骤6和7。突变分析已经被用来建立结构-功能关系：NH2-SAICAR合成酶-AIR羧基酶-COOH。SAICAR合成酶结构域的氨基酸序列与细菌PurC编码酶的氨基酸序列同源，随后的Air羧基酶结构域的序列与细菌纯编码酶的序列同源。在大肠杆菌中，空气羧化酶是PurEK基因的产物，其PurK亚基被认为在二氧化碳结合中起作用。禽类酶缺乏与Purk对应的序列，但在大肠杆菌中发挥作用。E.Colipur突变体的功能互补可用于克隆额外的禽类cDNA，用于从头合成嘌呤核苷酸。
We have used functional complementation of Escherichia coli pur mutants to clone avian cDNA encoding 5-aminoimidazole ribonucleotide (AIR) carboxylase-5-aminoimidazole-4-N-succinocarboxamide ribonucleotide (SAICAR) synthetase, the bifunctional enzyme catalyzing steps 6 and 7 in the pathway for de novo purine nucleotide synthesis. Mutational analyses have been used to establish the structure-function relationship: NH2-SAICAR synthetase-AIR carboxylase-COOH. The amino acid sequence of the SAICAR synthetase domain is homologous to that of bacterial purC-encoded enzymes, and the sequence of the following AIR carboxylase domain is homologous to that of bacterial purE-encoded enzymes. In E. coli, AIR carboxylase is the product of genes purEK with the purK subunit postulated to have a role in CO2 binding. The avian enzyme lacks sequences corresponding to purK yet functions in E. coli. Functional complementation of E. coli pur mutants can be used to clone additional avian cDNAs for de novo purine nucleotide synthetis.