期刊
TOXICON
卷 99, 期 -, 页码 68-72出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.toxicon.2015.03.007
关键词
Convergent evolution; Venom resistance; Honey badger; Nicotinic acetylcholine receptor; Mellivora capensis
资金
- Society for the Study of Evolution
- Department of Ecology, Evolution, and Behavior at the University of Minnesota
Honey badgers (Mellivora capensis) prey upon and survive bites from venomous snakes (Family: Elapidae), but the molecular basis of their venom resistance is unknown. The muscular nicotinic cholinergic receptor (nAChR), targeted by snake alpha-neurotoxins, has evolved in some venom-resistant mammals to no longer bind these toxins. Through phylogenetic analysis of mammalian nAChR sequences, we show that honey badgers, hedgehogs, and pigs have independently acquired functionally equivalent amino acid replacements in the toxin-binding site of this receptor. These convergent amino acid changes impede toxin binding by introducing a positively charged amino acid in place of an uncharged aromatic residue. In venom-resistant mongooses, different replacements at these same sites are glycosylated, which is thought to disrupt binding through steric effects. Thus, it appears that resistance to snake venom alpha-neurotoxin has evolved at least four times among mammals through two distinct biochemical mechanisms operating at the same sites on the same receptor. (C) 2015 Elsevier Ltd. All rights reserved.
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