Structure of the amantadine binding site of influenza M2 proton channels in lipid bilayers

Sarah D. Cady, Klaus Schmidt-Rohr, Jun Wang, Cinque S. Soto, William F. Degrado, Mei Hong

Research output: Contribution to journalArticle

442 Scopus citations

Abstract

The M2 protein of influenza A virus is a membrane-spanning tetrameric proton channel targeted by the antiviral drugs amantadine and rimantadine. Resistance to these drugs has compromised their effectiveness against many influenza strains, including pandemic H1N1. A recent crystal structure of M2(22-46) showed electron densities attributed to a single amantadine in the amino-terminal half of the pore, indicating a physical occlusion mechanism for inhibition. However, a solution NMR structure of M2(18-60) showed four rimantadines bound to the carboxy-terminal lipid-facing surface of the helices, suggesting an allosteric mechanism. Here we show by solid-state NMR spectroscopy that two amantadine-binding sites exist in M2 in phospholipid bilayers. The high-affinity site, occupied by a single amantadine, is located in the N-terminal channel lumen, surrounded by residues mutated in amantadine-resistant viruses. Quantification of the protein-amantadine distances resulted in a 0.3-resolution structure of the high-affinity binding site. The second, low-affinity, site was observed on the C-terminal protein surface, but only when the drug reaches high concentrations in the bilayer. The orientation and dynamics of the drug are distinct in the two sites, as shown by 2 H NMR. These results indicate that amantadine physically occludes the M2 channel, thus paving the way for developing new antiviral drugs against influenza viruses. The study demonstrates the ability of solid-state NMR to elucidate small-molecule interactions with membrane proteins and determine high-resolution structures of their complexes.

Original languageEnglish (US)
Pages (from-to)689-692
Number of pages4
JournalNature
Volume463
Issue number7281
DOIs
StatePublished - Feb 4 2010

ASJC Scopus subject areas

  • General

Fingerprint Dive into the research topics of 'Structure of the amantadine binding site of influenza M2 proton channels in lipid bilayers'. Together they form a unique fingerprint.

  • Cite this

    Cady, S. D., Schmidt-Rohr, K., Wang, J., Soto, C. S., Degrado, W. F., & Hong, M. (2010). Structure of the amantadine binding site of influenza M2 proton channels in lipid bilayers. Nature, 463(7281), 689-692. https://doi.org/10.1038/nature08722