Crystal structure of Mycobacterium tuberculosis 6-hydroxymethyl-7,8-dihydropteroate synthase in complex with pterin monophosphate:: New insight into the enzymatic mechanism and sulfa-drug action
Crystal structure of Mycobacterium tuberculosis 6-hydroxymethyl-7,8-dihydropteroate synthase in complex with pterin monophosphate:: New insight into the enzymatic mechanism and sulfa-drug action
复制标题
DOI：
10.1006/jmbi.2000.4094
复制
发表时间：
2000-10-06
影响因子：
5.6
通讯作者：
Hol, WGJ
中科院分区：
文献类型：
--
作者：
Baca, AM;Sirawaraporn, R;Hol, WGJ
6-羟甲基-7，8-二氢蝶酸合酶（DHPS）催化对氨基苯甲酸（pABA）与6-羟甲基-7，8-二氢蝶呤-焦磷酸缩合形成6-羟甲基-7，8-二氢蝶酸和焦磷酸。DHPS对于原核生物、低等真核生物和植物中叶酸的从头合成是必需的，但在哺乳动物中不存在。磺胺类和砜类药物抑制这种酶的活性会耗尽叶酸库，导致生长抑制和细胞死亡。在这里，我们报告了6-羟甲基蝶呤单磷酸（PtP）与来自结核分枝杆菌（Mtb）的DHPS的二元复合物的1.7埃分辨率晶体结构，结核分枝杆菌是每年导致数百万人死亡的病原体。与其他DHPS结构的比较表明，M。结核病DHPS结构是一个独特的构象，其中环1关闭的活性位点。Mtb DHPS结构暗示了一种机制，在该机制中，环1和2通过屏蔽活性位点免受本体溶剂的影响并允许焦磷酸转移发生而在催化中发挥重要作用。根据闭环1的新构象、氨苯砜和磺胺类药物抗性突变的分布、Mtb DHPS：PtP二元复合物中6-甲基碳原子与α-磷酸基桥连氧原子之间的键合方向、Mtb DHPS：PtP二元复合物中6-甲基碳原子与α-磷酸基桥连氧原子之间的键合方向、Mtb DHPS：PtP二元复合物中6-甲基碳原子与α-磷酸基桥连氧原子之间的键合方向、Mtb DHPS：PtP二元复合物中6-甲基碳原子与α-磷酸基桥连氧原子之间的键合方向以及Mtb DHPS：PtP二元复合物中6-甲基碳原子与α-磷酸基桥连氧原子之间的键合方向，提出了pABA与磺胺类药物和砜类药物的结合模式。和（iv）大肠杆菌DHPS结构中环2的构象。最后，Mtb DHPS结构揭示了一个高度保守的蝶呤结合口袋，可用于设计新型抗分枝杆菌药物。(C)北京大学出版社.
The enzyme 6-hydroxymethyl-7,8-dihydropteroate synthase (DHPS) catalyzes the condensation of para-aminobenzoic acid (pABA) with 6-hydroxymethyl-7,8-dihydropterin-pyrophosphate to form 6-hydroxymethyl-7,8-dihydropteroate and pyrophosphate. DHPS is essential for the de novo synthesis of folate in prokaryotes, lower eukaryotes, and in plants, but is absent in mammals. Inhibition of this enzyme's activity by sulfonamide and sulfone drugs depletes the folate pool, resulting in growth inhibition and cell death. Here, we report the 1.7 Angstrom resolution crystal structure of the binary complex of 6-hydroxymethylpterin monophosphate (PtP) with DHPS from Mycobacterium tuberculosis (Mtb), a pathogen responsible for the death of millions of human beings each year. Comparison to other DHPS structures reveals that the M. tuberculosis DHPS structure is in a unique conformation in which loop 1 closes over the active site. The Mtb DHPS structure hints at a mechanism in which both loops 1 and 2 play important roles in catalysis by shielding the active site from bulk solvent and allowing pyrophosphoryl transfer to occur. A binding mode for pABA, sulfonamides and sulfones is suggested based on: (i) the new conformation of the closed loop 1; (ii) the distribution of dapsone and sulfonamide resistance mutations; (iii) the observed direction of the bond between the 6-methyl carbon atom and the bridging oxygen atom to the alpha-phosphate group in the Mtb DHPS:PtP binary complex; and (iv) the conformation of loop 2 in the Escherichia coli DHPS structure. Finally, the Mtb DHPS structure reveals a highly conserved pterin binding pocket that may be exploited for the design of novel antimycobacterial agents. (C) 2000 Academic Press.