Leukotriene biosynthesis inhibitor MK886 impedes DNA polymerase activity.
Leukotriene biosynthesis inhibitor MK886 impedes DNA polymerase activity.
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DOI：
10.1021/tx300392m
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发表时间：
2013-02-18
影响因子：
4.1
通讯作者：
Eoff RL
中科院分区：
文献类型：
--
作者：
Ketkar A;Zafar MK;Maddukuri L;Yamanaka K;Banerjee S;Egli M;Choi JY;Lloyd RS;Eoff RL
专门的DNA聚合酶参与复制应激反应和DNA修复途径，这些途径起到了阻止细胞衰老和基因组不稳定的作用。这些事件可被肿瘤细胞作为化疗和电离放射治疗存活的机制，因此，代表了辅助治疗的潜在靶点。此前，由16,000种化合物组成的高通量筛选确定了几种第一代人类DNA聚合酶kappa(hPollκ)的原则证明抑制剂。吲哚衍生的5-脂氧合酶激活蛋白(FELP)抑制剂MK886是在该筛选中发现的最有效的HPOLκ抑制剂之一。然而，抑制的特异性和机制在很大程度上仍然不清楚。在本研究中，我们研究了MK886对人Y家族DNA聚合酶和一个模型B家族DNA聚合酶的特异性。MK886被发现对所有IC50值相似的DNA聚合酶的活性都有抑制作用，但对人DNA聚合酶ι的抑制效力增加了6到8倍，HPOL DNA聚合酶是一种高度容易出错的酶，在催化过程中使用霍格斯汀碱基配对模式。最近注释的25A.A.的加入部分取消了对hPollι的特异性。N端子扩展。根据Michaelis-Menten动力学分析和DNA结合分析，MK886的抑制机制似乎是混合的。在电子对接研究中，使用了一系列MK886与Y家族成员结合的模型。对接结果表明，两个结合口袋在Y家族聚合酶之间是保守的，而靠近拇指结构域的第三个口袋似乎是hPollι所独有的。总体而言，这些结果为MK886抑制DNA聚合酶的一般机制提供了深入的见解。
Specialized DNA polymerases participate in replication stress responses and in DNA repair pathways that function as barriers against cellular senescence and genomic instability. These events can be co-opted by tumor cells as a mechanism to survive chemotherapeutic and ionizing radiation treatments, and as such, represent potential targets for adjuvant therapies. Previously, a high-throughput screen of ~16,000 compounds identified several first generation proof-of-principle inhibitors of human DNA polymerase kappa (hpol κ). The indole-derived inhibitor of 5-lipoxygenase activating protein (FLAP), MK886, was one of the most potent inhibitors of hpol κ discovered in that screen. However, the specificity and mechanism of inhibition remained largely undefined. In the current study, the specificity of MK886 against human Y-family DNA polymerases and a model B-family DNA polymerase was investigated. MK886 was found to inhibit the activity of all DNA polymerases tested with similar IC50 values, the exception being a six- to eight-fold increase in the potency of inhibition against human DNA polymerase iota (hpol ι), a highly error-prone enzyme that uses Hoogsteen base-pairing modes during catalysis. The specificity against hpol ι was partially abrogated by inclusion of the recently annotated 25 a.a. N-terminal extension. Based on Michaelis-Menten kinetic analyses and DNA binding assays the mechanism of inhibition by MK886 appears to be mixed. In silico docking studies were used to produce a series of models for MK886 binding to Y-family members. The docking results indicate that two binding pockets are conserved between Y-family polymerases, while a third pocket near the thumb domain appears to be unique to hpol ι. Overall, these results provide insight into the general mechanism of DNA polymerase inhibition by MK886.
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