Characterization of novel small-molecule NRF2 activators: Structural and biochemical validation of stereospecific KEAP1 binding
Characterization of novel small-molecule NRF2 activators: Structural and biochemical validation of stereospecific KEAP1 binding
复制标题
DOI：
10.1016/j.bbagen.2016.07.026
复制
发表时间：
2016-11-01
影响因子：
3
通讯作者：
Wigley, W. Christian
中科院分区：
文献类型：
--
作者：
Huerta, Carlos;Jiang, Xin;Wigley, W. Christian
背景：半合成齐墩果烷三萜类抗氧化性炎症调节剂(TpAlm)是与Keap1半胱氨酸残基151(051)相互作用并激活NRF2的小分子。对tpAlms和Keap1之间结构-活性关系的探索受到齐墩三萜类五环结构的主要碳氢性质的限制。因此，我们使用新型的、化学上易处理的、人工合成的抗氧化剂炎症调节剂(SALM)来探索配体-蛋白质相互作用的立体选择性。方法：我们测量了NRF2激活的几个参数，以评估具有天然(tpAIM-like)4(S)、5(S)、10(R)和非天然4(R)、5(R)、10(S)构型的Saim手性对映体的效力。此外，我们还测定了两种不同sAlMS配合物中Keap1 BTB结构域的晶体结构。结果：我们发现在自然构型下，SAIME对映体的构型与tpAIM，RTA 405相似。引人注目的是，非自然构型的赛姆对映体的效力比自然构型的萨伊姆对映体弱10到40倍。结晶学研究表明，这些配体与C151形成共价键，并存在额外的氢键、Van der Waals相互作用和pi-堆积相互作用。结论：尽管tpAlms和sAIM激活NRF2需要Keap1 C151，但与其他Keap1残基的相互作用对这些配体的立体特异性识别和效力至关重要。一般意义：本工作表明，可逆的氰酮Michael受体，如tpAlms和sAlms，可以被特定地调整来调节关键信号分子上氧化还原敏感的半胱氨酸残基，这是一种具有重大创新药物开发前景的方法。(C)2016爱思唯尔B.V.保留所有权利。
Background: Semi-synthetic oleanane triterpenoid antioxidant inflammation modulators (tpAlMs) are small molecules that interact with KEAP1 cysteine residue 151 (051) and activate NRF2. Exploration of the structure-activity relationship between the tpAlMs and KEAP1 is limited by the predominantly hydrocarbon nature of the oleanane triterpenoid pentacyclic ring structure. Therefore, we used novel, chemically-tractable, synthetic antioxidant inflammation modulators (sAlMs) to probe the stereoselectivity of the ligand-protein interaction.Methods: We measured several parameters of NRF2 activation to assess the potency of sAIM enantiomers with natural (tpAIM-like) 4(S),5(S),10(R) or unnatural 4(R),5(R),10(S) configurations. Additionally, we determined the crystal structure of the KEAP1 BTB domain in complex with two different sAlMs.Results: We found that the potencies of sAIM enantiomers in the natural configuration were similar to those of the tpAIM, RTA 405. Strikingly, sAIM enantiomers in the unnatural configuration were 10- to 40-fold less potent than their natural counterparts. Crystallographic studies of sAlMs in complex with the KEAP1 BTB domain demonstrated that these ligands form a covalent bond with C151 and revealed the presence of additional hydrogen bonds, Van der Waals interactions, and pi-stacking interactions.Conclusions: Although KEAP1 C151 is required for NRF2 activation by tpAlMs and sAIMs, interactions with other KEAP1 residues are critical for the stereospecific recognition and potency of these ligands.General significance: This work demonstrates that reversible cyanoenone Michael acceptors, such as the tpAlMs and sAlMs, can be specifically tuned to regulate redox sensitive cysteine residues on key signaling molecules, an approach with significant promise for innovative drug development. (C) 2016 Elsevier B.V. All rights reserved.