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Backbone cyclization of analgesic conotoxin GeXIVA facilitates direct folding of the ribbon isomer

Journal Article


Abstract


  • Conotoxin GeXIVA inhibits the α9α10 nicotinic acetylcholine receptor (nAChR) and is analgesic in animal models of pain. α-Conotoxins have four cysteines that can have three possible disulfide connectivities: globular (Cys I –Cys III and Cys II –Cys IV ), ribbon (Cys I –Cys IV and Cys II –Cys III ), or bead (Cys I –Cys II and Cys III –Cys IV ). Native α-conotoxins preferably adopt the globular connectivity, and previous studies of α-conotoxins have focused on the globular isomers as the ribbon and bead isomers typically have lower potency at nAChRs than the globular form. A recent report showed that the bead and ribbon isomers of GeXIVA are more potent than the globular isomer, with low nanomolar half-maximal inhibitory concentrations (IC 50 ). Despite this high potency, the therapeutic potential of GeXIVA is limited, because like most peptides, it is susceptible to proteo-lytic degradation and is challenging to synthesize in high yield. Here we used backbone cyclization as a strategy to improve the folding yield as well as increase the serum stability of ribbon GeXIVA while preserving activity at the α9α10 nAChR. Specifically, cyclization of ribbon GeXIVA with a two-residue linker maintained the biological activity at the human α9α10 nAChR and improved stability in human serum. Short linkers led to selective formation of the ribbon disulfide isomer without requiring orthogonal protection. Overall, this study highlights the value of backbone cyclization in directing folding, improving yields, and stabilizing conotoxins with therapeutic potential.

UOW Authors


  •   Wu, Xiaosa (external author)
  •   Huang, Y H. (external author)
  •   Kaas, Quentin (external author)
  •   Harvey, Peta J. (external author)
  •   Wang, Conan K. (external author)
  •   Tae, Han Shen
  •   Adams, David
  •   Craik, David J. (external author)

Publication Date


  • 2017

Citation


  • Wu, X., Huang, Y., Kaas, Q., Harvey, P. J., Wang, C. K., Tae, H., Adams, D. J. & Craik, D. J. (2017). Backbone cyclization of analgesic conotoxin GeXIVA facilitates direct folding of the ribbon isomer. Journal of Biological Chemistry, 292 (41), 17101-17112.

Scopus Eid


  • 2-s2.0-85031322204

Number Of Pages


  • 11

Start Page


  • 17101

End Page


  • 17112

Volume


  • 292

Issue


  • 41

Place Of Publication


  • United States

Abstract


  • Conotoxin GeXIVA inhibits the α9α10 nicotinic acetylcholine receptor (nAChR) and is analgesic in animal models of pain. α-Conotoxins have four cysteines that can have three possible disulfide connectivities: globular (Cys I –Cys III and Cys II –Cys IV ), ribbon (Cys I –Cys IV and Cys II –Cys III ), or bead (Cys I –Cys II and Cys III –Cys IV ). Native α-conotoxins preferably adopt the globular connectivity, and previous studies of α-conotoxins have focused on the globular isomers as the ribbon and bead isomers typically have lower potency at nAChRs than the globular form. A recent report showed that the bead and ribbon isomers of GeXIVA are more potent than the globular isomer, with low nanomolar half-maximal inhibitory concentrations (IC 50 ). Despite this high potency, the therapeutic potential of GeXIVA is limited, because like most peptides, it is susceptible to proteo-lytic degradation and is challenging to synthesize in high yield. Here we used backbone cyclization as a strategy to improve the folding yield as well as increase the serum stability of ribbon GeXIVA while preserving activity at the α9α10 nAChR. Specifically, cyclization of ribbon GeXIVA with a two-residue linker maintained the biological activity at the human α9α10 nAChR and improved stability in human serum. Short linkers led to selective formation of the ribbon disulfide isomer without requiring orthogonal protection. Overall, this study highlights the value of backbone cyclization in directing folding, improving yields, and stabilizing conotoxins with therapeutic potential.

UOW Authors


  •   Wu, Xiaosa (external author)
  •   Huang, Y H. (external author)
  •   Kaas, Quentin (external author)
  •   Harvey, Peta J. (external author)
  •   Wang, Conan K. (external author)
  •   Tae, Han Shen
  •   Adams, David
  •   Craik, David J. (external author)

Publication Date


  • 2017

Citation


  • Wu, X., Huang, Y., Kaas, Q., Harvey, P. J., Wang, C. K., Tae, H., Adams, D. J. & Craik, D. J. (2017). Backbone cyclization of analgesic conotoxin GeXIVA facilitates direct folding of the ribbon isomer. Journal of Biological Chemistry, 292 (41), 17101-17112.

Scopus Eid


  • 2-s2.0-85031322204

Number Of Pages


  • 11

Start Page


  • 17101

End Page


  • 17112

Volume


  • 292

Issue


  • 41

Place Of Publication


  • United States