Multidrug and Toxin Extrusion (MATE) transporters are integral membrane proteins that move structurally unrelated lipophilic cations across the cell membrane by utilizing a preexisting sodium or proton gradient. Bacterial MATE transporters function as multidrug efflux pumps by expelling a cohort of antimicrobial agents from the cytoplasm, whereas their human counterparts mediate the excretion of various cytotoxic metabolites as well as therapeutic drugs. Given their functional relevance to the unwanted resistance to antimicrobials and chemotherapy, molecular structures of the MATE transporters will reveal not only how they transport their substrates across the cell membrane but also how their transport activity can be modulated in order to overcome drug resistance.
We aim to elucidate the molecular structure of an intact MATE transporter using X-ray crystallography. To date we have obtained crystals that diffract better than 3.8 E-resolution. Based on the crystal structure, we will construct various MATE mutants, reconstitute them into liposomes and characterize their transport properties utilizing substrate uptake assays. Our long-term objective is to decipher the molecular basis for multidrug binding and transport. Specifically, we seek to (1) establish the structures of a MATE transporter with and without drug substrates;(2) probe the transport mechanism via functional reconstitution of purified MATE transporters in liposomes;(3) determine the structures and drug-binding specificities of various MATE mutants. Our work will provide new insights into the general principles that govern multidrug binding and transport;it will also set the stage for structure-based design of pharmaceuticals targeting drug-resistant human pathogens and cancer cells.

Public Health Relevance

Multidrug resistance is a widespread and serious health issue. The proposed studies seek a deep understanding of multidrug transport, a key and evolutionarily conserved mechanism that underlies multidrug resistance. The proposed research has relevance to public health, because the findings are generally applicable to combating both drug- resistant pathogenic microorganisms as well as human cancer cells.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Biochemistry and Biophysics of Membranes Study Section (BBM)
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Chin, Jean
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Rosalind Franklin University
Schools of Medicine
North Chicago
United States
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Nie, Rongxin; Stark, Steven; Symersky, Jindrich et al. (2017) Structure and function of the divalent anion/Na+ symporter from Vibrio cholerae and a humanized variant. Nat Commun 8:15009
Lu, Min (2016) Structures of multidrug and toxic compound extrusion transporters and their mechanistic implications. Channels (Austin) 10:88-100
Radchenko, Martha; Nie, Rongxin; Lu, Min (2016) Disulfide Cross-linking of a Multidrug and Toxic Compound Extrusion Transporter Impacts Multidrug Efflux. J Biol Chem 291:9818-26
Symersky, Jindrich; Guo, Yi; Wang, Jimin et al. (2015) Crystallographic study of a MATE transporter presents a difficult case in structure determination with low-resolution, anisotropic data and crystal twinning. Acta Crystallogr D Biol Crystallogr 71:2287-96
Radchenko, Martha; Symersky, Jindrich; Nie, Rongxin et al. (2015) Structural basis for the blockade of MATE multidrug efflux pumps. Nat Commun 6:7995
Lu, Min; Symersky, Jindrich; Radchenko, Martha et al. (2013) Structures of a Na+-coupled, substrate-bound MATE multidrug transporter. Proc Natl Acad Sci U S A 110:2099-104
Lu, Min; Radchenko, Martha; Symersky, Jindrich et al. (2013) Structural insights into H+-coupled multidrug extrusion by a MATE transporter. Nat Struct Mol Biol 20:1310-7