Vinca alkaloid binding to P-glycoprotein occurs in a processive manner

Iqbal, Shagufta; Flux, Caitlin; Briggs, Deborah A.; Deplazes, Evelyne; Long, Jiansi; Skrzypek, Ruth; Rothnie, Alice; Kerr, Ian D.; Callaghan, Richard

Abstract

A mechanistic understanding of how P-glycoprotein (Pgp) is able to bind and transport its astonishing range of substrates remains elusive. Pharmacological data demonstrated the presence of at least four distinct binding sites, but their locations have not been fully elucidated. The combination of biochemical and structural data suggests that initial binding may occur in the central cavity or at the lipid-protein interface. Our objective was to define the binding sites for two transported substrates of Pgp; the anticancer drug vinblastine and the fluorescent probe rhodamine 123. A series of mutations was generated in positions proximal to previously defined drug-interacting residues on Pgp. The protein was purified and reconstituted into styrene-maleic acid lipid particles (SMALPs) to measure the apparent drug binding constant or into liposomes for assessment of drug-stimulated ATP hydrolysis. The biochemical data were reconciled with structural models of Pgp using molecular docking. The data indicated that the binding of rhodamine 123 occurred predominantly within the central cavity of Pgp. In contrast, the significantly more hydrophobic vinblastine bound to both the lipid-protein interface and within the central cavity. The data suggest that the initial interaction of vinca alkaloids with Pgp occurs at the lipid interface followed by internalisation into the central cavity, which also provides the transport conduit. This model is supported by recent structural observations with Pgp and early biophysical and cross-linking approaches. Moreover, the proposed model illustrates that the broad substrate profile for Pgp is underpinned by a combination of multiple initial interaction sites and an accommodating transport conduit.

Citation

Iqbal, S., Flux, C., Briggs, D. A., Deplazes, E., Long, J., Skrzypek, R., …Callaghan, R. (2022). Vinca alkaloid binding to P-glycoprotein occurs in a processive manner. BBA - Biomembranes, 1864(10), Article 184005. https://doi.org/10.1016/j.bbamem.2022.184005

• Journal Article Type: Article
• Acceptance Date: Jul 12, 2022
• Online Publication Date: Jul 22, 2022
• Publication Date: Oct 1, 2022
• Deposit Date: Jul 24, 2023
• Publicly Available Date: Jul 26, 2023
• Journal: Biochimica et Biophysica Acta (BBA) - Biomembranes
• Print ISSN: 0005-2736
• Electronic ISSN: 1879-2642
• Publisher: Elsevier BV
• Peer Reviewed: Peer Reviewed
• Volume: 1864
• Issue: 10
• Article Number: 184005
• DOI: https://doi.org/10.1016/j.bbamem.2022.184005
• Keywords: Cell Biology; Biochemistry; Biophysics
• Public URL: https://nottingham-repository.worktribe.com/output/23221044
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0005273622001432?via%3Dihub