Structure of Amantadine-Bound M2 Transmembrane Peptide of Influenza A in Lipid Bilayers from Magic-Angle-Spinning Solid-State NMR: The Role of Ser31 in Amantadine Binding

Cady, Sarah D.; Mishanina, Tatiana V.; Hong, Mei

doi:10.1016/j.jmb.2008.11.022

Cited by 136 publications

(208 citation statements)

References 57 publications

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“…Perhaps the most biologically relevant M2 structure comprises CD peptides in a DOPC/DOPE (dioleoylphosphatidylcholine/dioleoylphosphatidylethanolamine) bilayer at pH 7.5 [Protein Data Bank (PDB) ID: 2LOJ] (Sharma et al, 2010), although no drug molecule was bound. Recent drug-bound studies include a solid-state NMR structure in DMPC (dimyristoylphosphatidylcholine) bilayers with amantadine bound to the channel lumen (PDB ID: 2KQT) (Cady et al, 2009(Cady et al, , 2010, as well as solution structures of CD peptides in detergent micelles with four rimantadine molecules bound to a peripheral, membraneexposed binding site (PDB ID: 2RLF) (Schnell & Chou, 2008). Generally, solution structures show more compacted lumenal domains and a varied orientation of the C-terminal basic helices compared with solid-state structures.…”

Section: Iav M2mentioning

confidence: 99%

Viroporins: structure, function and potential as antiviral targets

Scott

Griffin

2015

Journal of General Virology

124

146

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The channel-forming activity of a family of small, hydrophobic integral membrane proteins termed 'viroporins' is essential to the life cycles of an increasingly diverse range of RNA and DNA viruses, generating significant interest in targeting these proteins for antiviral development. Viroporins vary greatly in terms of their atomic structure and can perform multiple functions during the virus life cycle, including those distinct from their role as oligomeric membrane channels. Recent progress has seen an explosion in both the identification and understanding of many such proteins encoded by highly significant pathogens, yet the prototypic M2 proton channel of influenza A virus remains the only example of a viroporin with provenance as an antiviral drug target. This review attempts to summarize our current understanding of the channel-forming functions for key members of this growing family, including recent progress in structural studies and drug discovery research, as well as novel insights into the life cycles of many viruses revealed by a requirement for viroporin activity. Ultimately, given the successes of drugs targeting ion channels in other areas of medicine, unlocking the therapeutic potential of viroporins represents a valuable goal for many of the most significant viral challenges to human and animal health.

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Section: Iav M2mentioning

confidence: 99%

Viroporins: structure, function and potential as antiviral targets

Scott

Griffin

2015

Journal of General Virology

124

146

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“…Those 2 studies have generated controversies, especially about the mechanism of drug inhibition. Additional structural results have recently been published that add to the controversies surrounding inhibitor binding (23,24) and the closed-to open-state conformational transition (25).Channel activation may involve conformations not captured by the X-ray and NMR structures. Indeed, solid-state NMR (9,23,(26)(27)(28) and other studies have shown that the M2 TMD possesses significant conformational heterogeneity.…”

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confidence: 99%

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confidence: 99%

Conformational heterogeneity of the M2 proton channel and a structural model for channel activation

Cross

Zhou

2009

Proc. Natl. Acad. Sci. U.S.A.

100

136

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The M2 protein of influenza virus A is a proton-selective ion channel activated by pH. Structure determination by solid-state and solution NMR and X-ray crystallography has contributed significantly to our understanding, but channel activation may involve conformations not captured by these studies. Indeed, solidstate NMR data demonstrate that the M2 protein possesses significant conformational heterogeneity. Here, we report molecular dynamics (MD) simulations of the M2 transmembrane domain (TMD) in the absence and presence of the antiviral drug amantadine. The ensembles of MD conformations for both apo and bound forms reproduced the NMR data well. The TMD helix was found to kink around Gly-34, where water molecules penetrated deeply into the backbone. The amantadine-bound form exhibited a single peak Ϸ10°in the distribution of helix-kink angle, but the apo form exhibited 2 peaks, Ϸ0°and 40°. Conformations of the apo form with small and large kink angles had narrow and wide pores, respectively, around the primary gate formed by His-37 and Trp-41. We propose a structural model for channel activation, in which the small-kink conformations dominate before proton uptake by His-37 from the exterior, and proton uptake makes the large-kink conformations more favorable, thereby priming His-37 for proton release to the interior.solid-state NMR ͉ MD simulations ͉ helix kink ͉ histidine tetrad ͉ amantadine T he M2 protein of influenza virus A is a proton-selective ion channel activated by pH. Its function, proton conductance, is essential for effective replication of the virus. The transmembrane domain (TMD) of this homotetrameric protein contains a single helix (residues Ser-22 to Leu-46) from each subunit. Within the TMD, residues His-37 and Trp-41 constitute the primary gate that is critical for proton conductance and selectivity and pH activation (1-3). On the N-terminal (i.e., virus exterior) side, disulfide bonds involving Cys-17 and Cys-19 provide stabilization (4). On the C-terminal side, an amphiphilic helix may also be involved in pH activation (5). The antiviral drug amantadine and its derivatives inhibit the channel function by putatively binding to the TMD (6-8). The structures of the M2 TMD in the apo form and the amantadine-bound form were first determined by solid-state NMR (9, 10). In addition, extensive experimental (1, 2, 11-16) and computational (17-20) studies have been performed to model the structure of the M2 TMD and understand the molecular mechanisms of conductance and selectivity of the proton channel. Recently, 2 new structures were solved by X-ray crystallography (21) and solution NMR spectroscopy (22). Those 2 studies have generated controversies, especially about the mechanism of drug inhibition. Additional structural results have recently been published that add to the controversies surrounding inhibitor binding (23,24) and the closed-to open-state conformational transition (25).Channel activation may involve conformations not captured by the X-ray and NMR structures. Indeed, solid-state NMR...

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“…2, pore site 2). The authors noted, however, that the drug amine is too far from Ser31 hydroxyl groups (~4.5 Å) to form hydrogen bonds (Cady et al, 2009). Although the experimental and modeling studies above all suggested interaction between amantadine and AM2, none of them directly showed the location of the binding site inside the pore.…”

Section: Drug Inhibition and Ongoing Controversymentioning

confidence: 98%

“…However, this site would not be consistent with the above neutron diffraction data. Recently, Cady et al suggested based on chemical shift changes measured by solid-state NMR that amantadine binds to yet another site inside the channel (Cady et al, 2009). In this binding site, the drug amino group points to the N-terminal end of the channel and is located around Ser31 (Fig.…”

Section: Drug Inhibition and Ongoing Controversymentioning

confidence: 99%

Flu channel drug resistance: a tale of two sites

Pielak

Chou

2010

Protein Cell

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The M2 proteins of influenza A and B virus, AM2 and BM2, respectively, are transmembrane proteins that oligomerize in the viral membrane to form proton-selective channels. Proton conductance of the M2 proteins is required for viral replication; it is believed to equilibrate pH across the viral membrane during cell entry and across the trans-Golgi membrane of infected cells during viral maturation. In addition to the role of M2 in proton conductance, recent mutagenesis and structural studies suggest that the cytoplasmic domains of the M2 proteins also play a role in recruiting the matrix proteins to the cell surface during virus budding. As viral ion channels of minimalist architecture, the membrane-embedded channel domain of M2 has been a model system for investigating the mechanism of proton conduction. Moreover, as a proven drug target for the treatment of influenza A infection, M2 has been the subject of intense research for developing new anti-flu therapeutics. AM2 is the target of two anti-influenza A drugs, amantadine and rimantadine, both belonging to the adamantane class of compounds. However, resistance of influenza A to adamantane is now widespread due to mutations in the channel domain of AM2. This review summarizes the structure and function of both AM2 and BM2 channels, the mechanism of drug inhibition and drug resistance of AM2, as well as the development of new M2 inhibitors as potential anti-flu drugs.

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Structure of Amantadine-Bound M2 Transmembrane Peptide of Influenza A in Lipid Bilayers from Magic-Angle-Spinning Solid-State NMR: The Role of Ser31 in Amantadine Binding

Cited by 136 publications

References 57 publications

Viroporins: structure, function and potential as antiviral targets

Viroporins: structure, function and potential as antiviral targets

Conformational heterogeneity of the M2 proton channel and a structural model for channel activation

Flu channel drug resistance: a tale of two sites

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