The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities.
The structure of Plasmodium falciparum serine hydroxymethyltransferase reveals a novel redox switch that regulates its activities.
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DOI：
10.1107/s1399004714005598
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发表时间：
2014-06
期刊：
影响因子：
--
通讯作者：
Leartsakulpanich U
中科院分区：
文献类型：
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作者：
Chitnumsub P;Ittarat W;Jaruwat A;Noytanom K;Amornwatcharapong W;Pornthanakasem W;Chaiyen P;Yuthavong Y;Leartsakulpanich U
恶性疟原虫SHMT的晶体结构揭示了控制功能活性的有趣的二硫键/巯基开关的快照。 恶性疟原虫丝氨酸羟甲基转移酶（PfSHMT）是dTMP合成循环中的一种酶，是抗疟靶标，因为其表达或功能的抑制已被证明对寄生虫是致命的。由于野生型酶不能结晶，因此进行了表面残基的蛋白质工程。成功地结晶了表面工程突变体PfSHMT-F292 E，并在3 μ m分辨率下确定了其结构。 PfSHMT-F292 E结构是PfSHMT的良好代表，因为该变体显示出与野生型相似的生化性质。虽然PfSHMT的整体结构与其他SHMT相似，但其独特的特征包括存在两个环和由四氢叶酸（THF）底物结合口袋中的Cys 125和Cys 364形成的独特半胱氨酸对。这些结构特征在其他SHMT中从未报道过。这两个残基的生物化学表征和突变分析证实，它们作为二硫键/巯基开关来调节该酶的THF依赖性催化功能。这种氧化还原开关不存在于人类酶中，其中不存在半胱氨酸对。这里报告的数据可以进一步利用作为一种新的策略，专门破坏寄生虫酶的活性，而不干扰人类酶的功能。
The crystal structure of P. falciparum SHMT revealed snapshots of an intriguing disulfide/sulfhydryl switch controlling the functional activity. Plasmodium falciparum serine hydroxymethyltransferase (PfSHMT), an enzyme in the dTMP synthesis cycle, is an antimalarial target because inhibition of its expression or function has been shown to be lethal to the parasite. As the wild-type enzyme could not be crystallized, protein engineering of residues on the surface was carried out. The surface-engineered mutant PfSHMT-F292E was successfully crystallized and its structure was determined at 3 Å resolution. The PfSHMT-F292E structure is a good representation of PfSHMT as this variant revealed biochemical properties similar to those of the wild type. Although the overall structure of PfSHMT is similar to those of other SHMTs, unique features including the presence of two loops and a distinctive cysteine pair formed by Cys125 and Cys364 in the tetrahydrofolate (THF) substrate binding pocket were identified. These structural characteristics have never been reported in other SHMTs. Biochemical characterization and mutation analysis of these two residues confirm that they act as a disulfide/sulfhydryl switch to regulate the THF-dependent catalytic function of the enzyme. This redox switch is not present in the human enzyme, in which the cysteine pair is absent. The data reported here can be further exploited as a new strategy to specifically disrupt the activity of the parasite enzyme without interfering with the function of the human enzyme.