TY - JOUR
T1 - Rimantadine Binds to and Inhibits the Influenza A M2 Proton Channel without Enantiomeric Specificity
AU - Thomaston, Jessica L.
AU - Samways, Marley L.
AU - Konstantinidi, Athina
AU - Ma, Chunlong
AU - Hu, Yanmei
AU - Bruce Macdonald, Hannah E.
AU - Wang, Jun
AU - Essex, Jonathan W.
AU - Degrado, William F.
AU - Kolocouris, Antonios
N1 - Funding Information:
J.L.T. and W.F.D. were supported by NIH grants R35-GM122603 and R01-GM117593. M.L.S. is supported by the EPSRC-funded CDT in Next Generation Computational Modeling, under grant EP/L015382/1. H.E.B.M acknowledges support from a Molecular Sciences Software Institute Fellowship and Relay Therapeutics. J.W. was supported by NIH grants AI119187 and AI144887. A.K. acknowledges support from Chiesi Hellas (SARG grant no. 10354). The use of the LCP crystallization robot was made possible by the National Center for Research Resources Grant 1S10RR027234-01.
Funding Information:
The authors thank Pil Seok Chae (Hanyang University, Seoul, South Korea) for providing the MNG detergent for crystallization trials. Data collection was carried out at ALS 8.3.1. Beamline 8.3.1 at the Advanced Light Source 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. The authors thank George Meigs and James Holton at ALS 8.3.1 for support during data collection. A.K. acknowledges the access to ARIS Supercomputer for the MD simulations using Desmond software. The authors acknowledge the use of the IRIDIS High-Performance Computing Facility and associated support services at the University of Southampton in the completion of this work.
Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/8/17
Y1 - 2021/8/17
N2 - The influenza A M2 wild-type (WT) proton channel is the target of the anti-influenza drug rimantadine. Rimantadine has two enantiomers, though most investigations into drug binding and inhibition have used a racemic mixture. Solid-state NMR experiments using the full length-M2 WT have shown significant spectral differences that were interpreted to indicate tighter binding for (R)- vs (S)-rimantadine. However, it was unclear if this correlates with a functional difference in drug binding and inhibition. Using X-ray crystallography, we have determined that both (R)- and (S)-rimantadine bind to the M2 WT pore with slight differences in the hydration of each enantiomer. However, this does not result in a difference in potency or binding kinetics, as shown by similar values for kon, koff, and Kd in electrophysiological assays and for EC50 values in cellular assays. We concluded that the slight differences in hydration for the (R)- and (S)-rimantadine enantiomers are not relevant to drug binding or channel inhibition. To further explore the effect of the hydration of the M2 pore on binding affinity, the water structure was evaluated by grand canonical ensemble molecular dynamics simulations as a function of the chemical potential of the water. Initially, the two layers of ordered water molecules between the bound drug and the channel's gating His37 residues mask the drug's chirality. As the chemical potential becomes more unfavorable, the drug translocates down to the lower water layer, and the interaction becomes more sensitive to chirality. These studies suggest the feasibility of displacing the upper water layer and specifically recognizing the lower water layers in novel drugs.
AB - The influenza A M2 wild-type (WT) proton channel is the target of the anti-influenza drug rimantadine. Rimantadine has two enantiomers, though most investigations into drug binding and inhibition have used a racemic mixture. Solid-state NMR experiments using the full length-M2 WT have shown significant spectral differences that were interpreted to indicate tighter binding for (R)- vs (S)-rimantadine. However, it was unclear if this correlates with a functional difference in drug binding and inhibition. Using X-ray crystallography, we have determined that both (R)- and (S)-rimantadine bind to the M2 WT pore with slight differences in the hydration of each enantiomer. However, this does not result in a difference in potency or binding kinetics, as shown by similar values for kon, koff, and Kd in electrophysiological assays and for EC50 values in cellular assays. We concluded that the slight differences in hydration for the (R)- and (S)-rimantadine enantiomers are not relevant to drug binding or channel inhibition. To further explore the effect of the hydration of the M2 pore on binding affinity, the water structure was evaluated by grand canonical ensemble molecular dynamics simulations as a function of the chemical potential of the water. Initially, the two layers of ordered water molecules between the bound drug and the channel's gating His37 residues mask the drug's chirality. As the chemical potential becomes more unfavorable, the drug translocates down to the lower water layer, and the interaction becomes more sensitive to chirality. These studies suggest the feasibility of displacing the upper water layer and specifically recognizing the lower water layers in novel drugs.
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U2 - 10.1021/acs.biochem.1c00437
DO - 10.1021/acs.biochem.1c00437
M3 - Article
C2 - 34342217
AN - SCOPUS:85113631836
VL - 60
SP - 2471
EP - 2482
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 32
ER -