Conotoxin TVIIA, a novel peptide from the venom of Conus tulipa (original) (raw)
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Three-dimensional structure of α-conotoxin EI determined by 1 H NMR spectroscopy
International Journal of Peptide Research and Therapeutics
Summary α-conotoxin EI is an 18-residue peptide (RDOCCYHPTCNMSNPQIC; 4–10, 5–18) isolated from the venom ofConus ermineus, the only fish-hunting cone snail of the Atlantic Ocean. This peptide targets specifically the nicotinic acetylcholine receptor (nAChR) found in mammalian skeletal muscle and the electric organTorpedo, showing a novel selectivity profile when compared to other α-conotoxins. The D structure of EI has been determined by 2D-NMR methods in combination with dynamical simulated annealing protocols. A total of 133 NOE-derived distances were used to produce 13 structures with minimum energy that complied with the NOE restraints. The structure of EI is characterized by a helical loop between THr9 and Met12 that is stabilized by the Cys4-Cys10 disulfide bond and turns involving Cys4-Cys5 and Asn14-Pro15. Other regions of the peptide appear to be flexible. The overall fold of EI is similar to that of other α4/7-conotoxins (PnIA/B, MII, EpI). However, unlike these other α4/7...
Conotoxins: Structure, Therapeutic Potential and Pharmacological Applications
Current pharmaceutical design, 2015
Cone snails, also known as marine gastropods, from Conus genus produce in their venom a diverse range of small pharmacologically active structured peptides called conotoxins. The cone snail venoms are widely unexplored arsenal of toxins with therapeutic and pharmacological potential, making them a treasure trove of ligands and peptidic drug leads. Conotoxins are small disulfide bonded peptides, which act as remarkable selective inhibitors and modulators of ion channels (calcium, sodium, potassium), nicotinic acetylcholine receptors, noradrenaline transporters, N-methyl-D-aspartate receptors, and neurotensin receptors. They are highly potent and specific against several neuronal targets making them valuable as research tools, drug leads and even therapeutics. In this review, we discuss their gene superfamily classification, nomenclature, post-translational modification, structural framework, pharmacology and medical applications of the active conopeptides. We aim to give an overview ...
Cloning, Synthesis and Functional Characterization of a Novel α-Conotoxin Lt1.3
Marine drugs, 2018
α-Conotoxins (α-CTxs) are small peptides composed of 11 to 20 amino acid residues with two disulfide bridges. Most of them potently and selectively target nicotinic acetylcholine receptor (nAChR) subtypes, and a few were found to inhibit the GABA receptor (GABAR)-coupled N-type calcium channels (Cav2.2). However, in all of α-CTxs targeting both receptors, the disulfide connectivity arrangement "C¹-C³, C²-C⁴" is present. In this work, a novel α4/7-CTx named Lt1.3 (GCCSHPACSGNNPYFC-NH₂) was cloned from the venom ducts of () in the South China Sea. Lt1.3 was then chemically synthesized and two isomers with disulfide bridges "C¹-C³, C²-C⁴" and "C¹-C⁴, C²-C³" were found and functionally characterized. Electrophysiological experiments showed that Lt1.3 containing the common disulfide bridges "C¹-C³, C²-C⁴" potently and selectively inhibited α3β2 nAChRs and not GABAR-coupled Cav2.2. Surprisingly, but the isomer with the disulfide bridges "C¹-C⁴,...
Structure and Sodium Channel Activity of an Excitatory I 1 -Superfamily Conotoxin, by
Biochemistry, 2007
Conotoxin ι-RXIA, from the fish-hunting species Conus radiatus, is a member of the recently characterized I 1 -superfamily, which contains eight cysteine residues arranged in a −C-C-CC-CC-C-C-pattern. ι-RXIA (formerly designated r11a) is one of three characterized I 1 peptides in which the third last residue is post-translationally isomerized to the D-configuration. Naturally occurring ι-RXIA with D-Phe44 is significantly more active as an excitotoxin than the L-Phe analogue both in vitro and in vivo. We have determined the solution structures of both forms by NMR spectroscopy, the first for an I 1 -superfamily member. The disulfide connectivities were determined from structure calculations and confirmed chemically as 5-19, 12-22, 18-27, and 21-38, suggesting that ι-RXIA has an ICK structural motif with one additional disulfide (21-38). Indeed, apart from the first few residues, the structure is well defined up to around residue 35 and does adopt an ICK structure. The C-terminal region, including Phe44, is disordered. Comparison of the D-Phe44 and L-Phe44 forms indicates that the switch from one enantiomer to the other has very little effect on the structure, even though it is clearly important for receptor interaction based on activity data. Finally, we identify the target of ι-RXIA as a voltage-gated sodium channel; ι-RXIA is an agonist, shifting the voltage dependence of activation of mouse Na V 1.6 expressed in Xenopus oocytes to more hyperpolarized potentials. Thus, there is a convergence of structure and function in ι-RXIA, as its disulfide pairing and structure resemble those of funnel web spider toxins that also target sodium channels.
Journal of Biological Chemistry, 2019
Venomous marine cone snails produce peptide toxins (conotoxins) that bind ion channels and receptors with high specificity and therefore are important pharmacological tools. Conotoxins contain conserved cysteine residues that form disulfide bonds that stabilize their structures. To gain structural insight into the large, yet poorly characterized conotoxin H-superfamily, we used NMR and CD spectroscopy along with MS-based analyses to investigate H-Vc7.2 from Conus victoriae, a peptide with a VI/VII cysteine framework. This framework has Cys I-Cys IV /Cys II-Cys V /Cys III-Cys VI connectivities, which have invariably been associated with the inhibitor cystine knot (ICK) fold. However, the solution structure of recombinantly expressed and purified H-Vc7.2 revealed that although it displays the expected cysteine connectivities, H-Vc7.2 adopts a different fold consisting of two stacked -hairpins with opposing -strands connected by two parallel disulfide bonds, a structure homologous to the N-terminal region of the human granulin protein. Using structural comparisons, we subsequently identified several toxins and nontoxin proteins with this "mini-granulin" fold. These findings raise fundamental questions concerning sequence-structure relationships within peptides and proteins and the key determinants that specify a given fold. Venoms from a variety of animals such as snakes, spiders, scorpions, and marine snails contain diverse peptide toxins that This work was supported in part by Danish Council for Independent Research Technology and Production Sciences Grant 7017-00288, Ulla og Mogens Folmer Andersens Fond, Fondation Juchum and Hørslev-Fonden (L. E.), and the Velux Foundations (K. T.). The authors declare that they have no conflicts of interest with the contents of this article. This article contains Figs. S1-S6, Tables S1-S6, and supporting Ref. 1. The atomic coordinates and structure factors (code 6Q5Z) have been deposited in the Protein Data Bank (http://wwpdb.org/). Chemical shifts have been deposited in the Biological Magnetic Resonance Bank with ID 34335.
The A-superfamily of Conotoxins: STRUCTURAL AND FUNCTIONAL DIVERGENCE
Journal of Biological Chemistry, 2004
The generation of functional novelty in proteins encoded by a gene superfamily is seldom well documented. In this report, we define the A-conotoxin superfamily, which is widely expressed in venoms of the predatory cone snails (Conus), and show how gene products that diverge considerably in structure and function have arisen within the same superfamily. A cDNA clone encoding ␣-conotoxin GI, the first conotoxin characterized, provided initial data that identified the A-superfamily. Conotoxin precursors in the A-superfamily were identified from six Conus species: most (11/16) encoded ␣-conotoxins, but some (5/16) belong to a family of excitatory peptides, the A-conotoxins that target voltagegated ion channels. ␣-Conotoxins are two-disulfidebridged nicotinic antagonists, 13-19 amino acids in length; A-conotoxins are larger (31-36 amino acids) with three disulfide bridges. Purification and biochemical characterization of one peptide, A-conotoxin MIVA is reported; five of the other predicted conotoxins were previously venom-purified. A comparative analysis of conotoxins purified from venom, and their precursors reveal novel post-translational processing, as well as mutational events leading to polymorphism. Patterns of sequence divergence and Cys codon usage define the major superfamily branches and suggest how these separate branches arose.
Design of Bioactive Peptides from Naturally Occurring -Conotoxin Structures
Journal of Biological Chemistry, 2012
Background: -Conotoxins possess interesting blocking effects on voltage-gated sodium channels (Na v s). Results: Based on two known -conotoxins, we designed miniaturized peptides that potently and selectively block Na v s, although they do not contain an ␣-helix. Conclusion: Peptidomimetics constitute a valuable tool to develop novel, synthetic Na v blockers. Significance: Our compounds prove to be an ideal starting platform in the search for therapeutics to treat Na v -related diseases.
Biochemistry, 1998
Conotoxins are valuable probes of receptors and ion channels because of their small size and highly selective activity. R-Conotoxin EpI, a 16-residue peptide from the mollusk-hunting Conus episcopatus, has the amino acid sequence GCCSDPRCNMNNPDY(SO 3 H)C-NH 2 and appears to be an extremely potent and selective inhibitor of the R3 2 and R3 4 neuronal subtypes of the nicotinic acetylcholine receptor (nAChR). The desulfated form of EpI ([Tyr 15 ]EpI) has a potency and selectivity for the nAChR receptor similar to those of EpI. Here we describe the crystal structure of [Tyr 15 ]EpI solved at a resolution of 1.1 Å using SnB. The asymmetric unit has a total of 284 non-hydrogen atoms, making this one of the largest structures solved de novo by direct methods. The [Tyr 15 ]EpI structure brings to six the number of R-conotoxin structures that have been determined to date. Four of these, [Tyr 15 ]EpI, PnIA, PnIB, and MII, have an R4/7 cysteine framework and are selective for the neuronal subtype of the nAChR. The structure of [Tyr 15 ]EpI has the same backbone fold as the other R4/7-conotoxin structures, supporting the notion that this conotoxin cysteine framework and spacing give rise to a conserved fold. The surface charge distribution of [Tyr 15 ]EpI is similar to that of PnIA and PnIB but is likely to be different from that of MII, suggesting that [Tyr 15 ]EpI and MII may have different binding modes for the same receptor subtype. a R-factor ) ∑|Fobs -Fcalc|/∑Fobs. b R-free as defined by Brünger (47). Crystal Structure of R-Conotoxin [Tyr 15 ]EpI