Mutations in dihydropteroate synthase are responsible for sulfone and sulfonamide resistance in Plasmodium falciparum
Mutations in dihydropteroate synthase are responsible for sulfone and sulfonamide resistance in Plasmodium falciparum
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DOI：
10.1073/pnas.94.25.13944
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发表时间：
1997-12-09
影响因子：
11.1
通讯作者：
Cowman, AF
中科院分区：
文献类型：
--
作者：
Triglia, T;Menting, JGT;Cowman, AF
恶性疟原虫是人类最严重的疟疾。在疟疾治疗中的一类重要药物是砜/磺酰胺类，其中磺胺是最常用的。磺胺的靶标是二氢蝶酸合酶（DHPS），并且DHPS基因的测序已经鉴定了可能参与对该药物的抗性机制的氨基酸差异。在这项研究中，我们已经测序的DHPS基因在10株来自泰国，并确定了一个新的等位基因的DHPS，有一个以前未确定的氨基酸差异。我们在大肠杆菌中表达了恶性疟原虫PPPK-DHPS的八个等位基因，并将功能酶纯化至同质。引人注目的是，硫代嘌呤的Ki值变化了几乎三个数量级，从敏感分离株的DHPS等位基因的0.14 μ M到高度抗性分离株中表达的酶的112 μ M。不同磺胺类药物和砜氨苯砜的Ki值的比较表明，DHPS中的氨基酸差异将赋予对这些化合物的交叉抗性。这些结果表明，恶性疟原虫的磺胺耐药分离株的DHPS酶中的氨基酸差异是对砜和磺胺类药物的抗性机制的核心，
Plasmodium falciparum causes the most severe form of malaria in humans. An important class of drugs in malaria treatment is the sulfone/sulfonamide group, of which sulfadoxine is the most commonly used, The target of sulfadoxine is the enzyme dihydropteroate synthase (DHPS), and sequencing of the DHPS gene has identified amino acid differences that may be involved in the mechanism of resistance to this drug. In this study we have sequenced the DHPS gene in 10 isolates from Thailand and identified a new allele of DHPS that has a previously unidentified amino acid difference. We have expressed eight alleles of P. falciparum PPPK-DHPS in Escherichia coli and purified the functional enzymes to homogeneity. Strikingly the K-i for sulfadoxine varies by almost three orders of magnitude from 0.14 mu M for the DHPS allele from sensitive isolates to 112 mu M for an enzyme expressed in a highly resistant isolate. Comparison of the K-i of different sulfonamides and the sulfone dapsone has suggested that the amino acid differences in DHPS would confer cross-resistance to these compounds, These results show that the amino acid differences in the DHPS enzyme of sulfadoxine-resistant isolates of P. falciparum are central to the mechanism of resistance to sulfones and sulfonamides,