Biological and structural evaluation of 10R- and 10S-methylthio-DDACTHF reveals a new role for sulfur in inhibition of glycinamide ribonucleotide transformylase.
Biological and structural evaluation of 10R- and 10S-methylthio-DDACTHF reveals a new role for sulfur in inhibition of glycinamide ribonucleotide transformylase.
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DOI：
10.1021/bi4005182
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发表时间：
2013-07-30
期刊：
影响因子：
2.9
通讯作者：
Wilson, Ian A.
中科院分区：
文献类型：
--
作者：
Connelly, Stephen;DeMartino, Jessica K.;Boger, Dale L.;Wilson, Ian A.
甘氨酰胺核糖核苷酸转化酶（GAR Tfase）是嘌呤从头生物合成途径中的叶酸依赖性酶，其长期以来被认为是开发抗肿瘤治疗剂的潜在靶标。在这里，我们报告了与人GAR Tfase结合的两种独立的C10非对映异构体10 S和10 R甲硫基-DDACTHF的生物学和X射线晶体学评价，包括迄今为止最高分辨率的载脂蛋白GAR Tfase结构（1.52 μ m）。两种非对映异构体均为GAR Tfase的强效抑制剂（10 R Ki = 210 nM，10 S Ki = 180 nM），并表现出对人白血病细胞生长的有效抑制（IC 50分别为80和50 nM）。它们的抑制活性令人惊讶地高，并且这些亲脂性C10取代的类似物显示出优于其亲水性对应物的明显优势，最引人注目的是在缺乏降低的叶酸载体蛋白活性的突变体人白血病细胞系中保留效力（IC 50分别= 70和60 nM）。结构表征揭示了这些二聚体的一种新的结合模式，其中亲脂性硫代甲基更深入地渗透到叶酸结合位点内的疏水口袋中。其他三种含硫叶酸类似物的计算机对接模拟也表明，这种疏水裂缝代表了一个有利的区域结合亲脂性取代基。总的来说，这些结果表明硫及其取代不仅在抗叶酸剂与GAR Tfase的结合中起重要作用，而且在选择性和细胞活性（生长抑制）中也起重要作用，从而为未来设计靶向GAR Tfase的有效和选择性抗叶酸剂药物提供了新的可能性。
Glycinamide ribonucleotide transformylase (GAR Tfase) is a folate-dependent enzyme in the de novo purine biosynthesis pathway, which has long been considered a potential target for development of anti-neoplastic therapeutics. Here we report the biological and X-ray crystallographic evaluations of both independent C10 diastereomers 10S and 10R methylthio-DDACTHF bound to human GAR Tfase, including the highest resolution apo GAR Tfase structure to date (1.52 Å). Both diastereomers are potent inhibitors (10R Ki = 210 nM, 10S Ki = 180 nM) of GAR Tfase and exhibit effective inhibition of human leukemia cell growth (IC50 = 80 and 50 nM, respectively). Their inhibitory activity was surprisingly high and these lipophilic C10-substituted analogs show distinct advantages over their hydrophilic counterparts, most strikingly in retaining potency in mutant human leukemia cell lines that lack reduced folate carrier protein activity (IC50 = 70 and 60 nM, respectively). Structural characterization reveals a new binding mode for these diasterisomers, in which the lipophilic thiomethyl groups penetrate deeper into a hydrophobic pocket within the folate-binding site. In silico docking simulations of three other sulfur-containing folate analogs also indicates that this hydrophobic cleft represents a favorable region for binding lipophilic substituents. Overall, these results suggest sulfur and its substitutions play an important role in not only the binding of anti-folates to GAR Tfase, but also in selectivity and cellular activity (growth inhibition), thereby presenting new possibilities for future design of potent and selective anti-folate drugs that target GAR Tfase.
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DOI：
10.1107/s0907444904019158
发表时间：
2004-12-01
影响因子：
2.2
作者：
Emsley, P;Cowtan, K
通讯作者：
Cowtan, K
影响因子：
3.6
作者：
Chen, ZH;Olopade, OI;Savarese, TM
通讯作者：
Savarese, TM
影响因子：
3.5
作者：
Cheng, H;Hwang, I;Boger, DL
通讯作者：
Boger, DL
影响因子：
3.4
作者：
Boritzki, TJ;Barlett, CA;Jackson, RC
通讯作者：
Jackson, RC
影响因子：
7.3
作者：
BIGHAM, EC;HODSON, SJ;FERONE, R
通讯作者：
FERONE, R