Role of Transmembrane Domain/Transmembrane Domain Interfaces of PGlycoprotein (ABCB1) in Solute Transport. Convergent Information from Photoaffinity Labeling, Site Directed Mutagenesis and in Silico Importance Prediction

Abstract

Human P-glycoprotein (P-gp, ABCB1) plays an important role in the development of resistance to anticancer therapy. This ABC-transporter (ATP-binding cassette transporter) intercepts drugs at the level of the plasma membrane and effluxes them before they are able to reach their intracellular target structures. Inhibition of P-gp by low molecular weight compounds has been advocated as a concept for resensitization of cells to anticancer agents and several clinical studies in oncological patients have advanced to phase III. Even more importantly, P-glycoprotein also represents an antitarget. Its expression in cells lining the intestinal tract, the canalicular side of hepatocytes, renal tubuli and the blood brain barrier lead to interference with pharmacokinetics of compounds that are recognized as pump substrates. An early prediction of ADMET (Absorption-Distribution-Metabolism-Excretion-Toxicity) properties is important during drug development, since interference of a compound with P-gp might compromise its future development into a drug. Despite considerable efforts, the mechanism by which P-gp binds and transports its solutes remains unclear. Generation of homology models of the protein allowed integration of data obtained by photoaffinity labeling, in silico prediction of functional importance by evolutionary tracing and site directed mutagenesis. An integral view of data indicates that these three lines of evidence converge to indicate two pseudosymmetric P-gp drug binding pockets located at the two transmembrane domain interfaces.

Structure–Activity Relationships, Ligand Efficiency, and Lipophilic Efficiency Profiles of Benzophenone-Type Inhibitors of the Multidrug Transporter P-Glycoprotein

“…In these studies, TM 3, 5, 6, 8, 10, 11, and 12 were identified as potential interacting helices. 30,46,47 This is well in line with our docking studies, which show main interactions with TM 5 and 6 near the entry gate and TM 7, 8, 9, and 12 deeper inside the cavity (SM Figure 4). No significant cluster of poses has been identified on the second wing (2/11 interface), which might be due to the asymmetry in the template used for building the homology model of P-gp, thus narrowing the available space at this side.…”

Chalcone Derivatives as Potential Inhibitors of P-Glycoprotein and NorA: An In Silico and In Vitro Study

“…A subsequent molecular docking study on the aforementioned chalcone derivatives was carried out, using a homology model of human P-gp developed from a crystallographic structure of the same transporter found in Mus musculus /house mouse (PDB ID 3g61) and the same docking protocol that was reported in our previous study [ 32 ]. The predicted ligand-binding site located at the interface of the transmembrane domains TM3 and TM11, as indicated in our 2016 paper and in agreement with results from other researchers (published in 2006 and 2009), was used as the docking site [ 32 , 35 , 36 ].…”

Molecular Dissection of Dual Pseudosymmetric Solute Translocation Pathways in Human P-Glycoprotein

“…Evolutionary pressure seems to have led to conservation of amino acid ensembles in the TMDs of P-gp (Chiba et al, 2006). This might enable binding pockets to procure redundant binding interactions with solutes.…”