A Novel Conotoxin Framework with a Helix-Loop-Helix (Cs /) Fold
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- 作者：Carolina Mö ; ller ; Sanaz Rahmankhah ; Janelle Lauer-Fields ; Jose Bubis ; Gregg B. Fields ; and Frank Marí
- 刊名：Biochemistry
- 出版年：2005
- 出版时间：December 13, 2005
- 年：2005
- 卷：44
- 期：49
- 页码：15986 - 15996
- 全文大小：1743K
- 年卷期：v.44,no.49(December 13, 2005)
- ISSN：1520-4995
文摘
Venomous predatory animals, such as snakes, spiders, scorpions, sea anemones, and conesnails, produce a variety of highly stable cystine-constrained peptide scaffolds as part of their neurochemicalstrategy for capturing prey. Here we report a new family of four-cystine, three-loop conotoxins (designatedframework 14). Three peptides of this family (flf14a-c) were isolated from the venom of Conus floridanusfloridensis, and one (vil14a) was isolated from the venom of Conus villepinii, two worm-hunting WesternAtlantic cone snail species. The primary structure for these peptides was determined using Edmandegradation sequencing, and their cystine pairing was assessed by limited hydrolysis with a combinationof CNBr and chymotrypsin under nonreducing, nonalkylating conditions in combination with MALDI-TOF MS analysis of the resulting peptidic fragments. CD spectra and nanoNMR spectroscopy of theseconotoxins directly isolated from the cone snails revealed a highly helical secondary structure for the fourconotoxins. Sequence-specific nanoNMR analysis at room temperature revealed a well-defined helix-loop-helix tertiary structure that resembles that of the Cs 
/ scorpion toxins 
-hefutoxin, -KTx1.3,and Om-toxins, which adopt a stable three-dimensional fold where the two -helices are linked by thetwo disulfide bridges. One of these conotoxins (vil14a) has a Lys/Tyr dyad, separated by approximately6Å, which is a conserved structural feature in K+ channel blockers. The presence of this framework inscorpions and in cone snails indicates a common molecular imprint in the venom of apparently unrelatedpredatory animals and suggests a common ancestral genetic origin.
/ scorpion toxins -hefutoxin, -KTx1.3,and Om-toxins, which adopt a stable three-dimensional fold where the two -helices are linked by thetwo disulfide bridges. One of these conotoxins (vil14a) has a Lys/Tyr dyad, separated by approximately6Å, which is a conserved structural feature in K+ channel blockers. The presence of this framework inscorpions and in cone snails indicates a common molecular imprint in the venom of apparently unrelatedpredatory animals and suggests a common ancestral genetic origin.