TY - JOUR
T1 - Inhibitors of the M2 Proton Channel Engage and Disrupt Transmembrane Networks of Hydrogen-Bonded Waters
AU - Thomaston, Jessica L.
AU - Polizzi, Nicholas F.
AU - Konstantinidi, Athina
AU - Wang, Jun
AU - Kolocouris, Antonios
AU - Degrado, William F.
N1 - Funding Information:
The authors thank Pil Seok Chae at Hanyang University (Seoul, South Korea) for providing MNG detergent and George Meigs and James Holton at ALS 8.3.1 for support during data collection. J.L.T., N.F.P., and W.F.D. were supported by NIH Grants GM122603 and GM117593. N.F.P. was supported by a T32 Grant from NIH (4 T32 HL 7731-25). J.W. was supported by NIH Grant AI119187. Use of the LCP crystallization robot was made possible by National Center for Research Resources Grant 1S10RR027234-01. This research used resources of the Advanced Light Source, a DOE Office of Science User Facility under Contract DE-AC02-05CH11231. Beamline 8.3.1 at the Advanced Light Source is operated by the University of California Office of the President, Multicampus Research Programs and Initiatives Grant MR-15-328599 and NIGMS Grants P30 GM124169 and R01 GM124149. A.K. thanks Chiesi Hellas, which supported this research (SARG 10354).
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/11/14
Y1 - 2018/11/14
N2 - Water-mediated interactions play key roles in drug binding. In protein sites with sparse polar functionality, a small-molecule approach is often viewed as insufficient to achieve high affinity and specificity. Here we show that small molecules can enable potent inhibition by targeting key waters. The M2 proton channel of influenza A is the target of the antiviral drugs amantadine and rimantadine. Structural studies of drug binding to the channel using X-ray crystallography have been limited because of the challenging nature of the target, with the one previously solved crystal structure limited to 3.5 Å resolution. Here we describe crystal structures of amantadine bound to M2 in the Inwardclosed conformation (2.00 Å), rimantadine bound to M2 in both the Inwardclosed (2.00 Å) and Inwardopen (2.25 Å) conformations, and a spiro-adamantyl amine inhibitor bound to M2 in the Inwardclosed conformation (2.63 Å). These X-ray crystal structures of the M2 proton channel with bound inhibitors reveal that ammonium groups bind to water-lined sites that are hypothesized to stabilize transient hydronium ions formed in the proton-conduction mechanism. Furthermore, the ammonium and adamantyl groups of the adamantyl-amine class of drugs are free to rotate in the channel, minimizing the entropic cost of binding. These drug-bound complexes provide the first high-resolution structures of drugs that interact with and disrupt networks of hydrogen-bonded waters that are widely utilized throughout nature to facilitate proton diffusion within proteins.
AB - Water-mediated interactions play key roles in drug binding. In protein sites with sparse polar functionality, a small-molecule approach is often viewed as insufficient to achieve high affinity and specificity. Here we show that small molecules can enable potent inhibition by targeting key waters. The M2 proton channel of influenza A is the target of the antiviral drugs amantadine and rimantadine. Structural studies of drug binding to the channel using X-ray crystallography have been limited because of the challenging nature of the target, with the one previously solved crystal structure limited to 3.5 Å resolution. Here we describe crystal structures of amantadine bound to M2 in the Inwardclosed conformation (2.00 Å), rimantadine bound to M2 in both the Inwardclosed (2.00 Å) and Inwardopen (2.25 Å) conformations, and a spiro-adamantyl amine inhibitor bound to M2 in the Inwardclosed conformation (2.63 Å). These X-ray crystal structures of the M2 proton channel with bound inhibitors reveal that ammonium groups bind to water-lined sites that are hypothesized to stabilize transient hydronium ions formed in the proton-conduction mechanism. Furthermore, the ammonium and adamantyl groups of the adamantyl-amine class of drugs are free to rotate in the channel, minimizing the entropic cost of binding. These drug-bound complexes provide the first high-resolution structures of drugs that interact with and disrupt networks of hydrogen-bonded waters that are widely utilized throughout nature to facilitate proton diffusion within proteins.
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U2 - 10.1021/jacs.8b06741
DO - 10.1021/jacs.8b06741
M3 - Article
C2 - 30165017
AN - SCOPUS:85053542958
VL - 140
SP - 15219
EP - 15226
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 45
ER -