M2 Proton Channel

M2 Proton Channel from Influenza A VirusM2 Proton Channel from Influenza A Virus

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BackgroundBackground

The M2 proton channel is a key protein that leads to viral infection [Takeuchi et al]. The M2 proton channel acidifies the viron which allows the viral matrix protein (M1) to disassociate from the ribonucleoprotein (RNP) [wu et al]. This allows the RNP to be transported to the nucleus of the cell [wu et al]. Several recent studies have looked at the effects of amantadine and rimantadine on inhibiting the transfer of protons through the M2 channel [stouffer et al]. It has been found that M2 is resistant to these two drugs in 90% of humans, birds and pigs stouffer et al]. Understanding the structure and function of this proton channel is necessary in solving the resistance problem [stouffer et al].

StructureStructure

The M2 proton channel from influenza A is 97 amino acid residues and forms a 24-residue N-terminal extracellular domain, a 19-residue trans-membrane domain, and a 54-residue C-terminal cytoplasmic domain [wu et al]. The 19-residue TM domain forms the highly selective proton channel [Takashi et al]. Circular dichroism spectra has shown the TM domain to form one α-helix that spans the membrane [wu et al]. By analytical ultracentrifugation, the TM domain is found to form [takeuchi et al]. This tetrameric bundle of the TM domain is found by NMR to be tilted by 25-38° from the channel axis [takeuchi et al]. The TM helicies are arranged around the channel pore with an approximate fourfold rotational symmetry [takeuchi et al].

pH GatingpH Gating

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