8P8J

Structure of 5D3-Fab and nanobody(Nb96)-bound ABCG2

Summary for 8P8J

• Entry DOI: 10.2210/pdb8p8j/pdb
• EMDB information: 17547
• Descriptor: ATP-binding cassette sub-family G member 2, 5D3(Fab) light chain variable domain, 5D3(Fab) heavy chain variable domain, ... (5 entities in total)
• Functional Keywords: membrane protein
• Biological source: Homo sapiens (human); More
• Total number of polymer chains: 7
• Total formula weight: 253792.55

Authors

Irobalieva, R.N.,Manolaridis, I.,Jackson, S.M.,Ni, D.,Pardon, E.,Stahlberg, H.,Steyaert, J.,Locher, K.P. (deposition date: 2023-06-01, release date: 2023-08-30, Last modification date: 2024-10-16)

Primary citation

Irobalieva, R.N.,Manolaridis, I.,Jackson, S.M.,Ni, D.,Pardon, E.,Stahlberg, H.,Steyaert, J.,Locher, K.P.
Structural Basis of the Allosteric Inhibition of Human ABCG2 by Nanobodies.
J.Mol.Biol., 435:168234-168234, 2023

PubMed Abstract: ABCG2 is an ATP-binding cassette transporter that exports a wide range of xenobiotic compounds and has been recognized as a contributing factor for multidrug resistance in cancer cells. Substrate and inhibitor interactions with ABCG2 have been extensively studied and small molecule inhibitors have been developed that prevent the export of anticancer drugs from tumor cells. Here, we explore the potential for inhibitors that target sites other than the substrate binding pocket of ABCG2. We developed novel nanobodies against ABCG2 and used functional analyses to select three inhibitory nanobodies (Nb8, Nb17 and Nb96) for structural studies by single particle cryo-electron microscopy. Our results showed that these nanobodies allosterically bind to different regions of the nucleotide binding domains. Two copies of Nb8 bind to the apex of the NBDs preventing them from fully closing. Nb17 binds near the two-fold axis of the transporter and interacts with both NBDs. Nb96 binds to the side of the NBD and immobilizes a region connected to key motifs involved in ATP binding and hydrolysis. All three nanobodies prevent the transporter from undergoing conformational changes required for substrate transport. These findings advance our understanding of the molecular basis of modulation of ABCG2 by external binders, which may contribute to the development of a new generation of inhibitors. Furthermore, this is the first example of modulation of human multidrug resistance transporters by nanobodies.

PubMed: 37597690
DOI: 10.1016/j.jmb.2023.168234

Experimental method

ELECTRON MICROSCOPY (3.49 Å)