1Q2J

Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 

wwPDB Validation   3D Report Full Report


This is version 2.1 of the entry. See complete history


Literature

Structural basis for tetrodotoxin-resistant sodium channel binding by mu-conotoxin SmIIIA.

Keizer, D.W.West, P.J.Lee, E.F.Yoshikami, D.Olivera, B.M.Bulaj, G.Norton, R.S.

(2003) J Biol Chem 278: 46805-46813

  • DOI: 10.1074/jbc.M309222200
  • Primary Citation of Related Structures:  
    1Q2J

  • PubMed Abstract: 
  • SmIIIA is a new micro-conotoxin isolated recently from Conus stercusmuscarum. Although it shares several biochemical characteristics with other micro-conotoxins (the arrangement of cysteine residues and a conserved arginine believed to interact with residues near the channel pore), it has several distinctive features, including the absence of hydroxyproline, and is the first specific antagonist of tetrodotoxin-resistant voltage-gated sodium channels to be characterized ...

    SmIIIA is a new micro-conotoxin isolated recently from Conus stercusmuscarum. Although it shares several biochemical characteristics with other micro-conotoxins (the arrangement of cysteine residues and a conserved arginine believed to interact with residues near the channel pore), it has several distinctive features, including the absence of hydroxyproline, and is the first specific antagonist of tetrodotoxin-resistant voltage-gated sodium channels to be characterized. It therefore represents a potentially useful tool to investigate the functional roles of these channels. We have determined the three-dimensional structure of SmIIIA in aqueous solution. Consistent with the absence of hydroxyprolines, SmIIIA adopts a single conformation with all peptide bonds in the trans configuration. The spatial orientations of several conserved Arg and Lys side chains, including Arg14 (using a consensus numbering system), which plays a key role in sodium channel binding, are similar to those in other micro-conotoxins but the N-terminal regions differ, reflecting the trans conformation for the peptide bond preceding residue 8 in SmIIIA, as opposed to the cis conformation in micro-conotoxins GIIIA and GIIIB. Comparison of the surfaces of SmIIIA with other micro-conotoxins suggests that the affinity of SmIIIA for TTX-resistant channels is influenced by the Trp15 side chain, which is unique to SmIIIA. Arg17, which replaces Lys in the other micro-conotoxins, may also be important. Consistent with these inferences from the structure, assays of two chimeras of SmIIIA and PIIIA in which their N- and C-terminal halves were recombined, indicated that residues in the C-terminal half of SmIIIA confer affinity for tetrodotoxin-resistant sodium channels in the cell bodies of frog sympathetic neurons. SmIIIA and the chimera possessing the C-terminal half of SmIIIA also inhibit tetrodotoxin-resistant sodium channels in the postganglionic axons of sympathetic neurons, as indicated by their inhibition of C-neuron compound action potentials that persist in the presence of tetrodotoxin.


    Organizational Affiliation

    The Walter & Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Mu-conotoxin SmIIIAA22Conus stercusmuscarumMutation(s): 0 
UniProt
Find proteins for P60207 (Conus stercusmuscarum)
Explore P60207 
Go to UniProtKB:  P60207
Protein Feature View
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  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
PCA
Query on PCA
AL-PEPTIDE LINKINGC5 H7 N O3GLN
Experimental Data & Validation

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 200 
  • Conformers Submitted: 20 
  • Selection Criteria: structures with the lowest energy 
  • OLDERADO: 1Q2J Olderado

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-02-24
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 2.0: 2019-12-25
    Changes: Data collection, Derived calculations, Polymer sequence
  • Version 2.1: 2020-06-24
    Changes: Database references, Derived calculations, Source and taxonomy, Structure summary