The relentless rise in multidrug resistance exerts devastating human and economic tolls, heralding a public health crisis. A major mechanism underlying multidrug resistance is mediated by integral membrane proteins called multidrug transporters, which can act as promiscuous molecular pumps to flush therapeutic drugs out of cells. Multidrug and toxic compound extrusion (MATE) proteins constitute a ubiquitous family of multidrug transporters and couple the efflux of structurally dissimilar, typically cationic compounds to the influx of Na+ or H+. The ~900 MATE transporters identified to date can be separated into the NorM, DinF (DNA-damage-inducible protein F) and eukaryotic subfamilies based on amino-acid sequence similarity. MATE transporters hold great appeal as novel therapeutic targets as they can extrude a litany of antibiotics, anticancer and diabetic drugs across cell membranes. The X-ray structures of several Na+-coupled NorM and H+-coupled DinF transporters, all captured in the extracellular-facing states, have been reported by us and others. Our substrate-bound structures in particular suggested how NorM and DinF transporters recognize and extrude cationic drugs via different mechanisms. Despite such triumphs, little is known about how a MATE transporter selects the counter-transported cation, or how it alternates between the extracellular- and intracellular-facing conformations to expel drugs. To fil such glaring gaps in our knowledge, we will elucidate the molecular structures of MATE transporters at conformation states distinct from the known structures. Based on those structures, we will deduce testable hypotheses, construct MATE mutants, and examine their transport function. Our long-term goal is to acquire a detailed, mechanistic understanding of multidrug transport. The current study will accomplish the following aims: (1) to determine the X-ray structures of H+- and Na+-coupled DinF transporters in their cation-bound states; (2) to visualize intracellular-facing MATE transporters by combining cross-linking with biochemical and crystallographic methods; (3) to enable mechanistic interpretation of our structures by conducting drug accumulation, antiport, efflux and resistance assays. Our findings will shine new light on the molecular underpinnings of multidrug resistance and open new vistas on therapeutic intervention.

Public Health Relevance

Multidrug resistance is looming as an escalating public health threat. The proposed work seeks a mechanistic understanding of multidrug transport, a major and evolutionarily conserved mechanism underpinning multidrug resistance. This research will benefit public health, as the findings will likely usher in new therapeutic opportunities for fightng against drug-resistant pathogenic microorganisms and human cancer cells.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM094195-07
Application #
9130221
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Chin, Jean
Project Start
2010-09-01
Project End
2019-08-31
Budget Start
2016-09-01
Budget End
2017-08-31
Support Year
7
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Rosalind Franklin University
Department
Biochemistry
Type
Schools of Medicine
DUNS #
069501252
City
North Chicago
State
IL
Country
United States
Zip Code
60064
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; 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
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