Poster Presentation 8th Venoms to Drugs 2023

Hydroxylation Of Prolines In Mu Conotoxins Increase Structural Stability And Potency At Sodium Channels. (#111)

Victoria Adegoke 1 , Ann C. Conibear 2 , Richard Clark 1 , Richard Lewis 3 , Johan Rosengren 1
  1. School of Biomedical Science, Faculty of Medicine, University of Queensland, St Lucia, Queensland, Australia
  2. Institute of Applied Synthetic Chemistry , Faculty of Technical Chemistry TU Wien, Vienna, Austria
  3. Institute of Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia

Conotoxins are disulfide-rich peptides isolated from the venoms of marine cone snails. In recent times, cone snails have become one of the most significant treasure troves of lead molecules for pharmaceutical development. Many conotoxins are highly modified with post-translational modifications (PTMs) such as hydroxylation of proline, C-terminal amidation, and glycosylation, amongst others. These modifications can alter the peptide's charge, size, and hydrophobicity, thereby influencing its interaction with target ion channels and modulating its potency and selectivity. In addition, PTMs can also affect the conformational stability and folding of the peptide, which can further impact its biological activity. Given the limited knowledge on the implications of PTMs with emphasis on proline hydroxylation and C-terminal amidation, the specific effect of PTMs on the structure and function of conotoxins needs to be investigated.

We investigated the role of these PTMs with the intent of providing novel insights and better clarity on whether the modification interacts directly with the binding site, changes the conotoxin structure, or affects the folding kinetics and biological activities of the conotoxin. Hence, we synthesised a set of eight conotoxin variants bearing PTM in the form of Hydroxylation of proline and C-terminal belonging to the Mu (ยต) pharmacological family of conotoxin, these conotoxins were selected because they contain naturally occurring PTMs in the peptide sequence, with modifications in their proline residue.

The presence of hydroxylation of proline PTM in these peptides had a significant impact on their biological activity, in vitro oxidative folding, and stability, but did not affect the structural activity of these peptides.

Taken together, our data suggest that proline hydroxylation is important for the in vitro oxidative folding, stability, and bioactivity of conotoxins, by demonstrating the key role proline hydroxylation PTM can have in the in vitro oxidative folding, overall structure, stability, and bioactivity of conotoxins.