Abstract
Cone snails are slow-moving animals that secure survival by injecting to their prey a concoction of highly potent and stable neurotoxic peptides called conotoxins. These small toxins (~ 10–30 AA) interact with ion channels and their diverse structures account for various variables such as the environment and the prey of preference. This study probed the conformational space of α-conotoxin PnIB from Conus pennaceus by performing all-atom molecular dynamics simulations on the conotoxin in complex solvent systems of water and octanol. Secondary structure analyses showed a uniform conformation for the pure (C100Oc, C100W) and minute (C95Oc, C5Oc) systems. In C50Oc, however, structural changes were observed. The original helices were converted to turns and were shown to happen simultaneously with the elongation of the helix and shortening of end-to-end distance. The transitions complement the orientation of the peptide at the interface. The shift to the broken helix conformation is marked by the rearrangement of solvent molecules to a framework that favors the accumulation of water molecules at residues 6–11 of the H2 region. This promotes specific protein–solvent interactions that facilitate secondary structure transitions. As PnIB has shown favorable binding toward neuronal nicotinic acetylcholine receptors, this study may provide insights on this conotoxin’s therapeutic potential.
Graphic abstract
Description: Structural changes in PnIB are accompanied by a simultaneous change in solvent density.
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Acknowledgements
The authors acknowledge the computational support provided by the High Performance Computing (HPC) facility under the Computing and Archiving Research Environment (CoARE) of the Department of Science and Technology - Advanced Science and Technology Institute (DOST-ASTI).
Funding
This work was funded by the Office of the Vice Chancellor for Research and Development (OVCRD) of the University of the Philippines Diliman (Project: 191922 ORG).
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Gaza, J.T., Sampaco, AR.B., Custodio, K.K.S. et al. Conformational dynamics of \(\alpha \)-conotoxin PnIB in complex solvent systems. Mol Divers 24, 1291–1299 (2020). https://doi.org/10.1007/s11030-019-09993-w
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DOI: https://doi.org/10.1007/s11030-019-09993-w