Parasite-specific inserts in the bifunctional S-adenosylmethionine decarboxylase/ornithine decarboxylase of Plasmodium falciparum modulate catalytic activities and domain interactions
Parasite-specific inserts in the bifunctional S-adenosylmethionine decarboxylase/ornithine decarboxylase of Plasmodium falciparum modulate catalytic activities and domain interactions
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DOI：
10.1042/bj20030614
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发表时间：
2004-01-15
影响因子：
4.1
通讯作者：
Louw, AI
中科院分区：
文献类型：
--
作者：
Birkholtz, LM;Wrenger, C;Louw, AI
多胺生物合成的疟疾寄生虫，恶性疟原虫。由分子量为330 kDa的单个铰链连接的双功能PfmMetDC/ODC [恶性疟原虫PfmMetDC（S-腺苷甲硫氨酸脱羧酶）/ODC（鸟氨酸脱羧酶）]调节。双功能的性质是独特的疟原虫和至少三个物种共享的CDMEDC/ODC。PfcidMetDC/ODC含有4个寄生虫特异性区域，大小范围为39至274个残基。寄生虫特异性插入的双功能蛋白的活性和蛋白质-蛋白质相互作用的意义进行了研究，通过一个单一的和多个删除策略。在双功能蛋白中缺失这些插入片段会降低相应的酶活性，并且在某些情况下也会降低相邻的非突变结构域的活性。ODC和ODC之间的分子间相互作用似乎对最佳ODC活性至关重要。已经报道了双功能恶性疟原虫二氢叶酸还原酶-胸苷酸合酶的类似结果[Yuvaniyama，Chitnumsub，Kamchonwongpaisan. Vanichtanankul，Sirawaraporn，Taylor，Walkinshaw和Yuthavong（2003）Nat.Struct.Biol.10，357-365]。共孵育的单功能，异源四聚体的约150 kDa的α MetDC结构域与单功能，同源二聚体的ODC结构域（约180 kDa）产生了一个活性的杂交复合物的330 kDa。铰链区是双功能复合物形成所必需的，并且仅间接地用于酶活性。ODC结构域中最小、最结构化和最保守的插入片段的缺失对两种脱羧酶、同源二聚体ODC排列和杂交复合物形成的活性影响最大。剩余的大插入物被预测为位于这些蛋白质表面上的非球状区域。与此相反的是，大的插入物在CIMetDC中不涉及混合复合物的形成，即使从其去除对两种催化活性的影响推断出该插入物和两个结构域之间的不同相互作用。因此，干扰寄生虫特异性区域介导的必需蛋白质-蛋白质相互作用似乎是一种可行的策略，以帮助设计选择性抑制剂的多胺代谢的黄疟原虫。
Polyamine biosynthesis of the malaria parasite, Plasmodium falciparum. is regulated by a single, hinge-linked bifunctional PfAdoMetDC/ODC [P. falciparum AdoMetDC (S-adenosylmethionine decarboxylase)/ODC (ornithine decarboxylase)] with a molecular mass of 330 kDa. The bifunctional nature of AdoMetDC/ODC is unique to Plasmodia and is shared by at least three species. The PfAdoMetDC/ODC contains four parasite-specific regions ranging in size from 39 to 274 residues. The significance of the parasite-specific inserts for activity and protein-protein interactions of the bifunctional protein was investigated by a single- and multiple-deletion strategy. Deletion of these inserts in the bifunctional protein diminished the corresponding enzyme activity and in some instances also decreased the activity of the neighbouring, non-mutated domain. Intermolecular interactions between AdoMetDC and ODC appear to be vital for optimal ODC activity. Similar results have been reported for the bifunctional P. falciparum dihydrofolate reductase-thymidylate synthase [Yuvaniyama, Chitnumsub, Kamchonwongpaisan. Vanichtanankul, Sirawaraporn, Taylor, Walkinshaw and Yuthavong (2003) Nat. Struct. Biol. 10, 357-365]. Co-incubation of the monofunctional, heterotetrameric approximate to 150 kDa AdoMetDC domain with the monofunctional, homodimeric ODC domain (approximate to 180 kDa) produced an active hybrid complex of 330 kDa. The hinge region is required for bifunctional complex formation and only indirectly for enzyme activities. Deletion of the smallest, most structured and conserved insert in the ODC domain had the biggest impact on the activities of both decarboxylases, homodimeric ODC arrangement and hybrid complex formation. The remaining large inserts are predicted to be non-globular regions located on the surface of these proteins. The large insert in AdoMetDC in contrast is not implicated in hybrid complex formation even though distinct interactions between this insert and the two domains are inferred from the effect of its removal on both catalytic activities. Interference with essential protein-protein interactions mediated by parasite-specific regions therefore appears to be a viable strategy to aid the design of selective inhibitors of polyamine metabolism of P. fialciparum.