Garrigues Alexia, Loiseau Nicolas, Delaforge Marcel, Ferté Jacques, Garrigos Manuel, André François, Orlowski Stéphane
Département de Biologie Joliot Curie, Commissariat à l'Energie Atomique, and Unité de Recherche Associée 2096 Centre National de la Recherche Scientifique, Laboratoire de Recherche Associé 17V Université Paris-Sud, Paris, France.
Mol Pharmacol. 2002 Dec;62(6):1288-98. doi: 10.1124/mol.62.6.1288.
The multidrug transporter P-glycoprotein is a plasma membrane protein involved in cell and tissue detoxification and the multidrug resistance (MDR) phenotype. It actively expels from cells a number of cytotoxic molecules, all amphiphilic but chemically unrelated. We investigated the molecular characteristics involved in the binding selectivity of P-glycoprotein by means of a molecular modeling approach using various substrates combined with an enzymological study using these substrates and native membrane vesicles prepared from MDR cells. We determined affinities and mutual relationships from the changes in P-glycoprotein ATPase activity induced by a series of cyclic peptides and peptide-like compounds, used alone or in combination. Modeling of the intramolecular distribution of the hydrophobic and polar surfaces of this series of molecules made it possible to superimpose some of these surface elements. These molecular alignments were correlated with the observed mutual exclusions for binding on P-glycoprotein. This led to the characterization of two different, but partially overlapping, pharmacophores. On each of these pharmacophores, the ligands compete with each other. The typical MDR-associated molecules, verapamil, cyclosporin A, and actinomycin D, bound to pharmacophore 1, whereas vinblastine bound to pharmacophore 2. Thus, the multispecific binding pocket of P-glycoprotein can be seen as sites, located near one another, that bind ligands according to the distribution of their hydrophobic and polar elements rather than their chemical motifs. The existence of two pharmacophores increases the possibilities for multiple chemical structure recognition. The size of the ligands affects their ability to compete with other ligands for binding to P-glycoprotein.
多药转运蛋白P-糖蛋白是一种质膜蛋白，参与细胞和组织解毒以及多药耐药（MDR）表型。它能主动将多种细胞毒性分子排出细胞，这些分子均具有两亲性但化学结构不相关。我们采用分子建模方法，使用各种底物，并结合酶学研究，利用这些底物和从MDR细胞制备的天然膜囊泡，研究了P-糖蛋白结合选择性所涉及的分子特征。我们通过一系列单独或组合使用的环肽和类肽化合物诱导的P-糖蛋白ATP酶活性变化，确定了亲和力和相互关系。对这一系列分子的疏水和极性表面的分子内分布进行建模，使得一些表面元素得以叠加。这些分子排列与观察到的在P-糖蛋白上结合的相互排斥相关。这导致了两种不同但部分重叠的药效基团的表征。在每个药效基团上，配体相互竞争。典型的与MDR相关的分子维拉帕米、环孢素A和放线菌素D与药效基团1结合，而长春碱与药效基团2结合。因此，P-糖蛋白的多特异性结合口袋可被视为彼此靠近的位点，这些位点根据配体的疏水和极性元素分布而非化学基序来结合配体。两种药效基团的存在增加了多种化学结构识别的可能性。配体的大小影响它们与其他配体竞争结合P-糖蛋白的能力。
