PDBsum entry 1ttl

Toxin

PDB id: 1ttl

Contents

Protein chain

28 a.a.

PDB id:

1ttl

Name:

Toxin

Title:

Omega-conotoxin gvia, a n-type calcium channel blocker

Structure:

Omega-conotoxin gvia. Chain: a. Fragment: gvic

Source:

Conus geographus. Geography cone. Organism_taxid: 6491. Secretion: venom

NMR struc:

20 models

Authors:

J.Mould,T.Yasuda,C.I.Schroeder,A.M.Beedle,C.J.Doering,G.W.Zamponi, D.J.Adams,R.J.Lewis

Key ref:

J.Mould et al. (2004). The alpha2delta auxiliary subunit reduces affinity of omega-conotoxins for recombinant N-type (Cav2.2) calcium channels. J Biol Chem, 279, 34705-34714. PubMed id: 15166237 DOI: 10.1074/jbc.M310848200

Date:

23-Jun-04 Release date: 13-Jul-04

Protein chain

P01522  (O16A_CONGE) -  Omega-conotoxin GVIA from Conus geographus

Seq: 73 a.a.

Struc: 28 a.a.*

* PDB and UniProt seqs differ at 4 residue positions (black crosses)

DOI no: 10.1074/jbc.M310848200

J Biol Chem 279:34705-34714 (2004)

PubMed id: 15166237

The alpha2delta auxiliary subunit reduces affinity of omega-conotoxins for recombinant N-type (Cav2.2) calcium channels.

J.Mould, T.Yasuda, C.I.Schroeder, A.M.Beedle, C.J.Doering, G.W.Zamponi, D.J.Adams, R.J.Lewis.

ABSTRACT

The omega-conotoxins from fish-hunting cone snails are potent inhibitors of voltage-gated calcium channels. The omega-conotoxins MVIIA and CVID are selective N-type calcium channel inhibitors with potential in the treatment of chronic pain. The beta and alpha(2)delta-1 auxiliary subunits influence the expression and characteristics of the alpha(1B) subunit of N-type channels and are differentially regulated in disease states, including pain. In this study, we examined the influence of these auxiliary subunits on the ability of the omega-conotoxins GVIA, MVIIA, CVID and analogues to inhibit peripheral and central forms of the rat N-type channels. Although the beta3 subunit had little influence on the on- and off-rates of omega-conotoxins, coexpression of alpha(2)delta with alpha(1B) significantly reduced on-rates and equilibrium inhibition at both the central and peripheral isoforms of the N-type channels. The alpha(2)delta also enhanced the selectivity of MVIIA, but not CVID, for the central isoform. Similar but less pronounced trends were also observed for N-type channels expressed in human embryonic kidney cells. The influence of alpha(2)delta was not affected by oocyte deglycosylation. The extent of recovery from the omega-conotoxin block was least for GVIA, intermediate for MVIIA, and almost complete for CVID. Application of a hyperpolarizing holding potential (-120 mV) did not significantly enhance the extent of CVID recovery. Interestingly, [R10K]MVIIA and [O10K]GVIA had greater recovery from the block, whereas [K10R]CVID had reduced recovery from the block, indicating that position 10 had an important influence on the extent of omega-conotoxin reversibility. Recovery from CVID block was reduced in the presence of alpha(2)delta in human embryonic kidney cells and in oocytes expressing alpha(1B-b). These results may have implications for the antinociceptive properties of omega-conotoxins, given that the alpha(2)delta subunit is up-regulated in certain pain states.

Selected figure(s)

Figure 4.
FIG. 4. Potency of -conotoxins at [1B] expressed in the presence or absence of 3 and [2] . A, potency estimates (K[d]) obtained from kinetic data in Tables I and II. B, potency estimates obtained from concentration-response curves at [1B-d] (n = 4-8 using six batches of oocytes) produced similar results. Current inhibition for [1B-d] + 3 or [1B-d] + 3 + [2] was evaluated at 7 or 10 min after starting toxin perfusion, respectively (see Fig. 5). Data indicated by the diamonds are from two batches of oocytes showing an unusually high sensitivity of [1B-d] + 3 to the block by -conotoxin MVIIA (n = 4-7). Error bars show S.E.

Figure 8.
FIG. 8. 1H NMR studies. A, H chemical shift for the three residue 10-substituted -conotoxins and their native counterparts. B, three-dimensional solution structures of MVIIA (accession number RCSB022889; Protein Data Bank (PDB) code 1TTK [PDB] ) (15), [R10K]MVIIA (accession number RCSB02280; PDB code 1TT3 [PDB] ) (15), GVIA (accession number RCSB0228890; PDB code 1TTL [PDB] ), and [O10K]GVIA (accession number RCSB022862; PDB code 1TR6 [PDB] ). Superimposition of the 20 lowest energy conformations across the entire backbone are shown with the exception of [O10K]GVIA, which was superimposed over residues 1-9 and 15-27.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 34705-34714) copyright 2004.

Figures were selected by the author.