Sandbox Reserved 932: Difference between revisions
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B. Dendrophila monomeric toxin (Denmotoxin) is the primary protein of snake venom used by ''Boiga dendrophila'' (fig. 1). This colubrid snake lives in Southest Asian lowland rainforest and mangrove swamps using birds as its primary prey. | B. Dendrophila monomeric toxin (Denmotoxin) is the primary protein of snake venom used by ''Boiga dendrophila'' (fig. 1). This colubrid snake lives in Southest Asian lowland rainforest and mangrove swamps using birds as its primary prey. It belongs to one of the most well characterized snake venom protein families is the Three-finger-toxins (3FTX). These proteins consist of three β-stranded finger-like polypeptide loops stabilized by four disulphide bridges on the surface of a globular core. In non-convential 3TFXs a fifth disulphide bridge can be present as is the case in Denmotoxin. The crystal structure of denmotoxin was solved to 1.9Å by molecular replacement method. <ref name=Dufton>Dufton M.J. & Hider R.C., [http://www.ncbi.nlm.nih.gov/pubmed/3277206 "Structure and pharmacology of elapid cytotoxins"], ''Pharmacol Ther. 1988;36(1):1-40'', 1988. Retrieved May 19, 2014.</ref><ref name=Endo>Endo T. & Tamiya N., Structure-function relationship of postsynaptic neurotoxins from snake venoms, ''Snake Toxins, pp. 165-222.'', 1991. Retrieved May 19, 2014.</ref> | ||
Denmotoxin binds specifically to bird muscle nicotinic acetylcholine receptors preventing their normal function in signal transduction. This taxon specifity is reached by unique structural differences to other 3FTXs such as changes in the suggested binding loop of the protein. <ref name=Pawlak>Pawlak J. ''et al.'', [http://www.ncbi.nlm.nih.gov/pubmed/16864572 "Denmotoxin, a Three-finger Toxin from the Colubrid Snake Boiga dendrophila (Mangrove Catsnake) with Bird-specific Activity"], ''The Journal of Biological Chemistry: 281: 29030-29041'', September 29, 2006. Retrieved May 19, 2014.</ref> | Denmotoxin binds specifically to bird muscle nicotinic acetylcholine receptors preventing their normal function in signal transduction. This taxon specifity is reached by unique structural differences to other 3FTXs such as changes in the suggested binding loop of the protein. <ref name=Pawlak>Pawlak J. ''et al.'', [http://www.ncbi.nlm.nih.gov/pubmed/16864572 "Denmotoxin, a Three-finger Toxin from the Colubrid Snake Boiga dendrophila (Mangrove Catsnake) with Bird-specific Activity"], ''The Journal of Biological Chemistry: 281: 29030-29041'', September 29, 2006. Retrieved May 19, 2014.</ref> | ||
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Three-finger toxins (3FTXs) are the most common family of snake venom proteins; these venoms can be found in elapid, colubrid and hydrophiid snakes and include toxins such as α-cobratoxin and α-bungarotoxin. 3FTXs are non-enzymatic proteins which form a structurally conserved superfamily whose members all share a highly conserved structure. <ref> | Three-finger toxins (3FTXs) are the most common family of snake venom proteins; these venoms can be found in elapid, colubrid and hydrophiid snakes and include toxins such as α-cobratoxin and α-bungarotoxin. 3FTXs are non-enzymatic proteins which form a structurally conserved superfamily whose members all share a highly conserved structure. <ref name=Dufton></ref><ref name=Endo></ref>The core structure of 3FTXs is formed by three <scene name='57/579702/Three_fingers/1'>three β-stranded polypeptide loops</scene> joined together by four conserved disulphide bridges located in the <scene name='57/579702/3ftx_beta_strands/2'>core</scene> of the protein. Despite the similarities in the structure of different toxins belonging to the family, the 3FTXs from various venoms have a variety of receptors/acceptors and exhibit differential responses in their targets. The members of the family can vary slightly in: the length and type of twists of the tree loops; the length and type of turns of the N and C-terminal tail and the amount of β-sheets in the overall structure. These differences allow for the specificity and toxicity of the proteins to their targets. <ref name=Pawlak/> | ||
Denmotoxin shares approximately 30% sequence similarity with other 3FTXs with an exception of exhibiting approximately 50% sequence similarity with another colubrid snake venom α-colubritoxin. Despite the relatively low sequence similarity, denmotoxin possesses all the residues needed to maintain the 3 finger fold. A large part of the sequence similarity between denmotoxin and other 3FTXs is due to the highly conserved disulphides and a number of structurally important residues. <ref name=Pawlak/> | Denmotoxin shares approximately 30% sequence similarity with other 3FTXs with an exception of exhibiting approximately 50% sequence similarity with another colubrid snake venom α-colubritoxin. Despite the relatively low sequence similarity, denmotoxin possesses all the residues needed to maintain the 3 finger fold. A large part of the sequence similarity between denmotoxin and other 3FTXs is due to the highly conserved disulphides and a number of structurally important residues. <ref name=Pawlak/> | ||
