M2 Proton Channel

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Contents 1 M2 Proton Channel from Influenza A Virus 2 Background 3 Structure 4 Central Cavity 5 pH Gating 6 References

M2 Proton Channel from Influenza A Virus

spinqualitylabelsall models The closed state structure of M2 protein H+ channel by solid state NMR spectroscopy [Stouffer et al, 2008]. Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Background

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 ^[1] and [Schnell et al] on inhibiting the transfer of protons through the M2 channel ^[2]. It has been found that M2 is resistant to these two drugs in 90% of humans, birds and pigs ^[3]. Understanding the structure and function of this proton channel is necessary in solving the resistance problem ^[2].

Structure

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 trameric helices form a left-handed bundle that resembles a truncated cone ^[2]. The TM helicies are arranged around the channel pore with an approximate fourfold rotational symmetry [takeuchi et al].

Central Cavity

spinqualitylabelsall models High resolution Crystal structure of Transmembrane domain of M2 protein [Stouffer et al, 2008] Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

pH Gating

References

1. ↑ Nishimura K, Kim S, Zhang L, Cross TA. The closed state of a H+ channel helical bundle combining precise orientational and distance restraints from solid state NMR. Biochemistry. 2002 Nov 5;41(44):13170-7. PMID:12403618
2. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named Stouffer
3. ↑ Nishimura K, Kim S, Zhang L, Cross TA. The closed state of a H+ channel helical bundle combining precise orientational and distance restraints from solid state NMR. Biochemistry. 2002 Nov 5;41(44):13170-7. PMID:12403618