Structural characteristics of the M2 protein of influenza a viruses: Evidence that it forms a tetrameric channe

Sugrue, Richard J.; Hay, Alan J.

doi:10.1016/0042-6822(91)90075-m

Cited by 426 publications

(361 citation statements)

References 22 publications

Supporting

Mentioning

348

Contrasting

Unclassified

Order By: Relevance

“…This conductance is in agreement with the values found for the TM domain of the peptide in our study. M2 is formed by a pair of covalently linked dimers (57,58). M2 expressed in Spodoptera frugiperda (Sf9) cells and reconstituted in lipid membranes exhibits conductances >25 pS (59).…”

Section: Discussionmentioning

confidence: 99%

Transmembrane Peptide NB of Influenza B: A Simulation, Structure, and Conductance Study

et al. 2000

View full text Add to dashboard Cite

The putative transmembrane segment of the ion channel forming peptide NB from influenza B was synthesized by standard solid-phase peptide synthesis. Insertion into the planar lipid bilayer revealed ion channel activity with conductance levels of 20, 61, 107, and 142 pS in a 0.5 M KCl buffer solution. In addition, levels at -100 mV show conductances of 251 and 413 pS. A linear current-voltage relation reveals a voltage-independent channel formation. In methanol and in vesicles the peptide appears to adopt an R-helical-like structure. Computational models of R-helix bundles using N ) 4, 5, and 6 NB peptides per bundle revealed water-filled pores after 1 ns of MD simulation in a solvated lipid bilayer. Calculated conductance values [using HOLE (Smart et al. (1997) Biophys. J. 72, 1109-1126] of ca. 20, 60, and 90 pS, respectively, suggested that the multiple conductance levels seen experimentally must correspond to different degrees of oligomerization of the peptide to form channels.In the genome of influenza B, RNA segment 6 encodes two integral membrane proteins, NB and NA. NB is a protein of ca. 100 amino acids. It has ca. 18 extramembraneous residues on its N-terminal end, a 22-residue membrane spanning segment, and a ca. 60 residue long C-terminal end (1, 2). NB is expressed at the surface of infected cells (3)(4)(5). In the virion the N-terminal site is located at the external surface. Experiments with gold immunolabeled freezefractured virions indicate that the C-terminus is located at the inside of the virion (4). By analogy with the M2 protein of influenza A, it was suggested (reviewed in ref 6) that NB might be a channel-forming protein.Conductance measurements with purified NB expressed in Escherichia coli and reconstituted in lipid bilayers reveal a conductance of 45 pS. However, when NB is incorporated in liposomes and then added to planar lipid bilayers, the conductance ranged from ca. 10 pS at very low NB concentration in the liposomes to several hundred picosiemens for higher concentrations (7). At neutral pH the channels are more permeable for sodium ions than chloride ions (P Na /P Cl ≈ 9 at pH 6.5). In asymmetrical NaCl solutions at pH 2.5 the permeability is higher for chloride ions (P Cl / P Na ≈ 4). A recent study on NB expressed in the plasmalemma of MEL 1 cells showed that the channel peptides induce a Na + -dependent proton current and a pH-activated Cl -current (8).One way in which single integral membrane proteins can form ion channels is via oligomerization to form a bundle of transmembrane helices. For the analogous channel peptide in influenza A, M2, it is believed that a tetrameric R-helix bundle is the minimal form of the proton-permeable ion channel (9-11). For NB the number of subunits in the bundle is not known. Purification of NB on gels using nonreducing conditions revealed the formation of disulfide-linked dimers and higher oligomers (2). Molecular modeling studies on bundles of the transmembrane parts of the peptide have been performed in vacuo with four, five, and si...

show abstract

Section: Discussionmentioning

confidence: 99%

Transmembrane Peptide NB of Influenza B: A Simulation, Structure, and Conductance Study

et al. 2000

View full text Add to dashboard Cite

show abstract

“…In addition to the AP helices, a pair of N-terminal cysteines, Cys17 and Cys19, have been shown to form intermolecular disulfides in vivo (Holsinger and Lamb, 1991;Sugrue and Hay, 1991). Although these cysteines are not required for channel function, they are conserved in nature and may play a role in keeping the tetramer together in the open state.…”

Section: The Open State Of the Am2 Channelmentioning

confidence: 99%

“…In influenza virus A and B, the M2 proteins, referred here as AM2 and BM2, respectively, are single-span membrane proteins of around 100 residues, which tetramerize in the viral membrane to form pH-dependent proton channels (Holsinger and Lamb, 1991;Sugrue and Hay, 1991;Paterson et al, 2003). It was first recognized in influenza A that the role of the proton channel is to equilibrate pH across the viral membrane during entry and across the trans-Golgi membrane of infected cells during viral maturation (Hay et al, 1985;Helenius, 1992;Pinto et al, 1992).…”

Section: Introductionmentioning

confidence: 99%

“…It consists of three segments: an extracellular N-terminal segment (residues 1-23), a transmembrane (TM) segment (residues 24-46), and an intracellular C-terminal segment (residues 47-97). Crosslinking experiments showed that the channel is formed by a parallel tetrameric array of AM2 monomers, in which the formation of intermonomer disulfide bonds at Cys17 and Cys19 may stabilize, but are not essential for, oligomeric assembly (Holsinger and Lamb, 1991;Sugrue and Hay, 1991). Mutagenesis studies have identified two pore-lining residues important for channel function; His37 is essential for channel activity and proton selectivity (Wang et al, 1995), and Trp41 is important for unidirectional conductance (Tang et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Flu channel drug resistance: a tale of two sites

Pielak

Chou

2010

Protein Cell

View full text Add to dashboard Cite

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.

show abstract

“…M2(H37A) is an integral membrane protein, whereas the other toxic proteins currently in use are cytosolic. Because M2(H37A) requires proper assembly as a tetramer within the secretory pathway to function (Sugrue and Hay, 1991;Pinto and Lamb, 2005), the death of any cell will not induce "leaky," secondary toxicity in neighboring cells. Conversely, cytosolic toxins have a risk of inducing unwanted secondary toxicity if endocytosed by neighboring cells.…”

Section: M2(h37a) Targeted Cellablation Versus Other Toxic Protein Symentioning

confidence: 99%

Targeted cell‐ablation in Xenopus embryos using the conditional, toxic viral protein M2(H37A)

Smith¹,

Kotecha²,

Towers³

et al. 2007

Developmental Dynamics

View full text Add to dashboard Cite

Harnessing toxic proteins to destroy selective cells in an embryo is an attractive method for exploring details of cell fate and cell-cell interdependency. However, no existing "suicide gene" system has proved suitable for aquatic vertebrates. We use the M2(H37A) toxic ion channel of the influenza-A virus to induce cell-ablations in Xenopus laevis. M2(H37A) RNA injected into blastomeres of early stage embryos causes death of their progeny by late-blastula stages. Moreover, M2(H37A) toxicity can be controlled using the M2 inhibitor rimantadine. We have tested the ablation system using transgenesis to target M2 (

show abstract

Structural characteristics of the M2 protein of influenza a viruses: Evidence that it forms a tetrameric channe

Cited by 426 publications

References 22 publications

Transmembrane Peptide NB of Influenza B: A Simulation, Structure, and Conductance Study

Transmembrane Peptide NB of Influenza B: A Simulation, Structure, and Conductance Study

Flu channel drug resistance: a tale of two sites

Targeted cell‐ablation in Xenopus embryos using the conditional, toxic viral protein M2(H37A)

Contact Info

Product

Resources

About