4HUN

MATE transporter NorM-NG in complex with R6G and monobody

Summary for 4HUN

• Entry DOI: 10.2210/pdb4hun/pdb
• Related: 4HUK 4HUL 4HUM
• Descriptor: Multidrug efflux protein, protein B, RHODAMINE 6G (3 entities in total)
• Functional Keywords: transport protein
• Biological source: Neisseria gonorrhoeae; More
• Total number of polymer chains: 2
• Total formula weight: 61078.12

Authors

Lu, M. (deposition date: 2012-11-02, release date: 2013-02-06, Last modification date: 2024-02-28)

Primary citation

Lu, M.,Symersky, J.,Radchenko, M.,Koide, A.,Guo, Y.,Nie, R.,Koide, S.
Structures of a Na+-coupled, substrate-bound MATE multidrug transporter.
Proc.Natl.Acad.Sci.USA, 110:2099-2104, 2013

PubMed Abstract: Multidrug transporters belonging to the multidrug and toxic compound extrusion (MATE) family expel dissimilar lipophilic and cationic drugs across cell membranes by dissipating a preexisting Na(+) or H(+) gradient. Despite its clinical relevance, the transport mechanism of MATE proteins remains poorly understood, largely owing to a lack of structural information on the substrate-bound transporter. Here we report crystal structures of a Na(+)-coupled MATE transporter NorM from Neisseria gonorrheae in complexes with three distinct translocation substrates (ethidium, rhodamine 6G, and tetraphenylphosphonium), as well as Cs(+) (a Na(+) congener), all captured in extracellular-facing and drug-bound states. The structures revealed a multidrug-binding cavity festooned with four negatively charged amino acids and surprisingly limited hydrophobic moieties, in stark contrast to the general belief that aromatic amino acids play a prominent role in multidrug recognition. Furthermore, we discovered an uncommon cation-π interaction in the Na(+)-binding site located outside the drug-binding cavity and validated the biological relevance of both the substrate- and cation-binding sites by conducting drug resistance and transport assays. Additionally, we uncovered potential rearrangement of at least two transmembrane helices upon Na(+)-induced drug export. Based on our structural and functional analyses, we suggest that Na(+) triggers multidrug extrusion by inducing protein conformational changes rather than by directly competing for the substrate-binding amino acids. This scenario is distinct from the canonical antiport mechanism, in which both substrate and counterion compete for a shared binding site in the transporter. Collectively, our findings provide an important step toward a detailed and mechanistic understanding of multidrug transport.

PubMed: 23341609
DOI: 10.1073/pnas.1219901110

Experimental method

X-RAY DIFFRACTION (3.59 Å)