Snake Venom and the Nicotinic Acetylcholine Receptor

Tom Goddard
September 18, 2013.

A look at how multibanded krait snake venom interacts with the nicotinic acetylcholine receptor that mediates nerve activation of muscles. This is a follow-on to the Chimera multi-scale brain demo.

Snake researcher, Joe Slowinski, was killed by a pencil size multibanded krait in Burma in 2001. Venom halts neoron control of muscles stopping breathing. Called the "5 step snake" in Vietnam war because you would die within 5 steps of being bitten -- really takes 8 hours or more. Second most common species for deadly snake bites in Taiwan.

Nicotinic acetylcholine
receptor, 4aq5.
Receptor pore transmits sodium and potassium ions. Receptor hydrophobicity.
Krait venom and 18 amino acid receptor fragment, 1idg. Venom aligned to receptor. Receptor fragment in pink does not match yellow receptor.
Krait venom and fragment, NMR ensemble, 1idh. Venom morph. Movie. Snail/human receptor with venom, 4hqp, July 2013.
Snail/human receptor with venom. Compare venom binding, 1idg, 4hqp.
Acetylcholine binding protein, 2xz5. Bound acetylcholine. Acetylcholine and venom bind in same location
(venom red/green, acetylcholine pink/orange, receptor yellow).

Crystal Structures

About 90% of molecular models with atomic detail are determined by x-ray crystallography. Here's a look at a crystallography density map.

Acetylcholine receptor and venom, 4hqp. 12 copies in unit cell. 2 unit cells.
3 by 3 by 3 unit cells, surface for each protein.
X-ray density. Density with atomic model