Organisation and sequence determination of glutamine-dependent carbamoyl phosphate synthetase II in Toxoplasma gondii
Organisation and sequence determination of glutamine-dependent carbamoyl phosphate synthetase II in Toxoplasma gondii
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DOI：
10.1016/s0020-7519(02)00214-x
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发表时间：
2003-01-01
影响因子：
4
通讯作者：
Bzik, DJ
中科院分区：
文献类型：
--
作者：
Fox, BA;Bzik, DJ
氨甲酰基磷酸合成酶II编码从头嘧啶生物合成的第一个酶步骤。氨甲酰磷酸合成酶II是弓形虫复制和毒力所必需的。在这项研究中，我们的特点是一个28 kb的基因编码弓形虫氨甲酰磷酸合成酶II的一级结构。氨甲酰磷酸合成酶II基因被36个内含子中断。由37个氨甲酰磷酸合成酶II外显子编码的预测蛋白质是具有与C-末端氨甲酰磷酸合成酶结构域融合的N-末端谷氨酰胺酰胺转移酶结构域的1，687个氨基酸的多肽。这种双功能组织的氨甲酰磷酸合成酶II是独特的，到目前为止，原生动物寄生虫从门Apicomplexa（疟原虫，巴贝虫，弓形虫）或动物寄生虫（锥虫，利什曼原虫）。顶复门寄生虫拥有最大的氨甲酰磷酸合成酶II酶，由于插入在谷氨酰胺酰胺转移酶和氨甲酰磷酸合成酶结构域，不存在于相应的基因片段从细菌，植物，真菌和哺乳动物。C-末端变构调节结构域，氨甲酰磷酸合成酶连接结构域和寡聚化结构域也不同于其他物种中的相应结构域。新的C-末端调节结构域可以解释缺乏激活弓形虫氨甲酰磷酸合成酶II的变构效应5-磷酸核糖1-焦磷酸。弓形虫在体外的生长显着抑制谷氨酰胺拮抗剂acivicin，谷氨酰胺转移酶活性的抑制剂通常与氨甲酰磷酸合成酶II，鸟苷一磷酸合成酶，或CTP合成酶。(C)2002年澳大利亚寄生虫学学会有限公司由爱思唯尔科技有限公司出版。保留所有权利。
Carbamoyl phosphate synthetase II encodes the first enzymic step of de novo pyrimidine biosynthesis. Carbamoyl phosphate synthetase II is essential for Toxoplasma gondii replication and virulence. In this study, we characterised the primary structure of a 28 kb gene encoding Toxoplasma gondii carbamoyl phosphate synthetase II. The carbamoyl phosphate synthetase II gene was interrupted by 36 introns. The predicted protein encoded by the 37 carbamoyl phosphate synthetase II exons was a 1,687 amino acid polypeptide with an N-terminal glutamine amidotransferase domain fused with C-terminal carbamoyl phosphate synthetase domains. This bifunctional organisation of carbamoyl phosphate synthetase II is unique, so far, to protozoan parasites from the phylum Apicomplexa (Plasmodium, Babesia, Toxoplasma) or zoomastigina (Trypanosoma, Leishmania). Apicomplexan parasites possessed the largest carbamoyl phosphate synthetase II enzymes due to insertions in the glutamine amidotransferase and carbamoyl phosphate synthetase domains that were not present in the corresponding gene segments from bacteria, plants, fungi and mammals. The C-terminal allosteric regulatory domain, the carbamoyl phosphate synthetase linker domain and the oligomerisation domain were also distinct from the corresponding domains in other species. The novel C-terminal regulatory domain may explain the lack of activation of Toxoplasma gondii carbamoyl phosphate synthetase II by the allosteric effector 5-phosphoribosyl 1-pyrophosphate. Toxoplasma gondii growth in vitro was markedly inhibited by the glutamine antagonist acivicin, an inhibitor of glutamine amidotransferase activity typically associated with carbamoyl phosphate synthetase II, guanosine monophosphate synthetase, or CTP synthetase. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.