Laboratory of Enzyme Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 118 55 Athina, Greece.
Turku Bioscience Centre, University of Turku and Åbo Akademi University, 20521 Turku, Finland.
Int J Mol Sci. 2022 Mar 25;23(7):3606. doi: 10.3390/ijms23073606.
Glutathione transferases (GSTs; EC 2.5.1.18) form a group of multifunctional enzymes that are involved in phase II of the cellular detoxification mechanism and are associated with increased susceptibility to cancer development and resistance to anticancer drugs. The present study aims to evaluate the ligandability of the human GSTM1-1 isoenzyme (hGSTM1-1) using a broad range of structurally diverse pesticides as probes. The results revealed that hGSTM1-1, compared to other classes of GSTs, displays limited ligandability and ligand-binding promiscuity, as revealed by kinetic inhibition studies. Among all tested pesticides, the carbamate insecticide pirimicarb was identified as the strongest inhibitor towards hGSTM1-1. Kinetic inhibition analysis showed that pirimicarb behaved as a mixed-type inhibitor toward glutathione (GSH) and 1-chloro-2,4-dinitrobenzene (CDNB). To shine a light on the restricted hGSTM1-1 ligand-binding promiscuity, the ligand-free crystal structure of hGSTM1-1 was determined by X-ray crystallography at 1.59 Å-resolution. Comparative analysis of ligand-free structure with the available ligand-bound structures allowed for the study of the enzyme's plasticity and the induced-fit mechanism operated by hGSTM1-1. The results revealed important structural features of the H-site that contribute to xenobiotic-ligand binding and specificity. It was concluded that hGSTM1-1 interacts preferentially with one-ring aromatic compounds that bind at a discrete site which partially overlaps with the xenobiotic substrate binding site (H-site). The results of the study form a basis for the rational design of new drugs targeting hGSTM1-1.
谷胱甘肽转移酶（GSTs；EC 2.5.1.18）形成了一组多功能酶，它们参与细胞解毒机制的第二阶段，并且与癌症发展的易感性增加和对抗癌药物的耐药性有关。本研究旨在使用广泛的结构多样的农药作为探针来评估人 GSTM1-1 同工酶（hGSTM1-1）的配体结合能力。结果表明，与其他 GST 类相比，hGSTM1-1 的配体结合能力和配体结合的混杂性有限，这是通过动力学抑制研究揭示的。在所测试的所有农药中，氨基甲酸酯类杀虫剂咪鲜胺被鉴定为对 hGSTM1-1 最强的抑制剂。动力学抑制分析表明，咪鲜胺对谷胱甘肽（GSH）和 1-氯-2,4-二硝基苯（CDNB）表现为混合型抑制剂。为了阐明 hGSTM1-1 受限的配体结合混杂性，通过 X 射线晶体学以 1.59 Å 的分辨率确定了 hGSTM1-1 的无配体晶体结构。无配体结构与现有配体结合结构的比较分析允许研究酶的可塑性和 hGSTM1-1 操作的诱导契合机制。结果揭示了 H 位有助于外源性配体结合和特异性的重要结构特征。结论是 hGSTM1-1 优先与一个环芳香族化合物相互作用，该化合物结合在一个离散的位点，该位点部分与外源性底物结合位点（H 位）重叠。该研究结果为针对 hGSTM1-1 的新药的合理设计奠定了基础。
