Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors

Drew Everhart, G. Edward Cartier, Arun Malhotra, Aldrin V Gomes, J. Michael McIntosh, Charles W. Luetje

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

α-Conotoxin MII, a peptide toxin isolated from Conus magus, antagonizes a subset of neuronal nicotinic receptors. Rat α3β2 receptors, expressed in Xenopus oocytes, are blocked with an IC50 of 3.7 ± 0.3 nM. To identify structural features that determine toxin potency, a series of alanine-substituted toxins were synthesized and tested for the ability to block the function of α3β2 receptors. Circular dichroism and protein modeling were used to assess the structural integrity of the mutant toxins. Three residues were identified as major determinants of toxin potency. Replacement of asparagine 5, proline 6, or histidine 12 with alanine resulted in >2700-fold, 700-fold, and ∼2700-fold losses in toxin potency, respectively. A decrease in pH improved toxin potency, while an increase in pH eliminated toxin blockade, suggesting that, in the active form of the toxin, histidine 12 is charged. The imidazole ring of histidine 12 protrudes from one side, while asparagine 5 and proline 6 are located at the opposite end of the toxin structure. The side chains of these three residues are exposed on the surface of the toxin, suggesting that they directly interact with the α3β2 receptor.

Original languageEnglish (US)
Pages (from-to)2732-2737
Number of pages6
JournalBiochemistry
Volume43
Issue number10
DOIs
StatePublished - Mar 16 2004
Externally publishedYes

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Conotoxins
Nicotinic Receptors
Histidine
Asparagine
Proline
Alanine
Peptides
Structural integrity
Circular Dichroism
Xenopus
Inhibitory Concentration 50
Oocytes
Rats
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Everhart, D., Cartier, G. E., Malhotra, A., Gomes, A. V., McIntosh, J. M., & Luetje, C. W. (2004). Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors. Biochemistry, 43(10), 2732-2737. https://doi.org/10.1021/bi036180h

Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors. / Everhart, Drew; Cartier, G. Edward; Malhotra, Arun; Gomes, Aldrin V; McIntosh, J. Michael; Luetje, Charles W.

In: Biochemistry, Vol. 43, No. 10, 16.03.2004, p. 2732-2737.

Research output: Contribution to journalArticle

Everhart, D, Cartier, GE, Malhotra, A, Gomes, AV, McIntosh, JM & Luetje, CW 2004, 'Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors', Biochemistry, vol. 43, no. 10, pp. 2732-2737. https://doi.org/10.1021/bi036180h
Everhart D, Cartier GE, Malhotra A, Gomes AV, McIntosh JM, Luetje CW. Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors. Biochemistry. 2004 Mar 16;43(10):2732-2737. https://doi.org/10.1021/bi036180h
Everhart, Drew ; Cartier, G. Edward ; Malhotra, Arun ; Gomes, Aldrin V ; McIntosh, J. Michael ; Luetje, Charles W. / Determinants of Potency on α-Conotoxin MII, a Peptide Antagonist of Neuronal Nicotinic Receptors. In: Biochemistry. 2004 ; Vol. 43, No. 10. pp. 2732-2737.
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