Outward open conformation of a Major Facilitator Superfamily multidrug/H+ antiporter provides insights into switching mechanism

• Published in: Nature communications 2018-10, Vol.9 (1), p.4005-9, Article 4005
• Main Authors: Nagarathinam, Kumar, Nakada-Nakura, Yoshiko, Parthier, Christoph, Terada, Tohru, Juge, Narinobu, Jaenecke, Frank, Liu, Kehong, Hotta, Yunhon, Miyaji, Takaaki, Omote, Hiroshi, Iwata, So, Nomura, Norimichi, Stubbs, Milton T., Tanabe, Mikio
• Format: Article
• Language: English
• Subjects: 101/1; 631/45/535/1266; 631/45/612/1237; 82/83; Amino Acid Substitution; Antiporters - chemistry; Antiporters - genetics; Antiporters - metabolism; Cell Membrane - metabolism; Chloramphenicol - metabolism; Computer simulation; Conformation; Crystal structure; Crystallography, X-Ray; Drug Resistance, Multiple - physiology; E coli; Efflux; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Humanities and Social Sciences; Hydrogen; Hydrophobic and Hydrophilic Interactions; Ligands; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; Models, Molecular; Molecular dynamics; Molecular Dynamics Simulation; multidisciplinary; Multidrug resistance; Protein Structure, Secondary; Protein Transport; Science; Science (multidisciplinary); Structure-Activity Relationship; Switching
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-06306-x

Multidrug resistance (MDR) poses a major challenge to medicine. A principle cause of MDR is through active efflux by MDR transporters situated in the bacterial membrane. Here we present the crystal structure of the major facilitator superfamily (MFS) drug/H + antiporter MdfA from Escherichia coli in an outward open conformation. Comparison with the inward facing (drug binding) state shows that, in addition to the expected change in relative orientations of the N- and C-terminal lobes of the antiporter, the conformation of TM5 is kinked and twisted. In vitro reconstitution experiments demonstrate the importance of selected residues for transport and molecular dynamics simulations are used to gain insights into antiporter switching. With the availability of structures of alternative conformational states, we anticipate that MdfA will serve as a model system for understanding drug efflux in MFS MDR antiporters. The multidrug resistance transporter mediated efflux of antibiotics from the bacterial cytoplasm represents a major challenge to medicine. Here authors solve the X-ray crystallographic structure of the drug/H+ antiporter MdfA from Escherichia coli and shed light on the conformational switching mechanism.