Parker Lorien J, Bocedi Alessio, Ascher David B, Aitken Jade B, Harris Hugh H, Lo Bello Mario, Ricci Giorgio, Morton Craig J, Parker Michael W
ACRF Rational Drug Discovery Centre, St. Vincent's Institute of Medical Research, Fitzroy, Victoria, 3065, Australia.
Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia.
Protein Sci. 2017 Feb;26(2):317-326. doi: 10.1002/pro.3084. Epub 2016 Dec 14.
Arsenic-based compounds are paradoxically both poisons and drugs. Glutathione transferase (GSTP1-1) is a major factor in resistance to such drugs. Here we describe using crystallography, X-ray absorption spectroscopy, mutagenesis, mass spectrometry, and kinetic studies how GSTP1-1 recognizes the drug phenylarsine oxide (PAO). In conditions of cellular stress where glutathione (GSH) levels are low, PAO crosslinks C47 to C101 of the opposing monomer, a distance of 19.9 Å, and causes a dramatic widening of the dimer interface by approximately 10 Å. The GSH conjugate of PAO, which forms rapidly in cancerous cells, is a potent inhibitor (K = 90 nM) and binds as a di-GSH complex in the active site forming part of a continuous network of interactions from one active site to the other. In summary, GSTP1-1 can detoxify arsenic-based drugs by sequestration at the active site and at the dimer interface, in situations where there is a plentiful supply of GSH, and at the reactive cysteines in conditions of low GSH.
基于砷的化合物具有矛盾性，既是毒药又是药物。谷胱甘肽转移酶（GSTP1-1）是对此类药物产生抗性的一个主要因素。在此，我们描述了利用晶体学、X射线吸收光谱、诱变、质谱和动力学研究，GSTP1-1如何识别药物苯胂氧化物（PAO）。在细胞应激条件下，当谷胱甘肽（GSH）水平较低时，PAO将相对单体的C47与C101交联，距离为19.9 Å，并使二聚体界面显著加宽约10 Å。PAO的GSH共轭物在癌细胞中迅速形成，是一种强效抑制剂（K = 90 nM），并作为双GSH复合物结合在活性位点上，形成从一个活性位点到另一个活性位点的连续相互作用网络的一部分。总之，在GSH供应充足的情况下，GSTP1-1可以通过在活性位点和二聚体界面螯合来解毒基于砷的药物；在GSH水平较低的情况下，则通过与反应性半胱氨酸结合来解毒。
