Download MendeleyThe three-dimensional structural surface of two beta-sheet scorpion toxins mimics that of an alpha-helical dihydropyridine receptor segment.
Green, D., Pace, S., Curtis, S.M., Sakowska, M., Lamb, G.D., Dulhunty, A.F., Casarotto, M.G.(2003) Biochem J 370: 517-527
- PubMed: 12429019
- DOI: https://doi.org/10.1042/BJ20021488
- Primary Citation of Related Structures:
1JZP - PubMed Abstract:
An alpha-helical II-III loop segment of the dihydropyridine receptor activates the ryanodine receptor calcium-release channel. We describe a novel manipulation in which this agonist's activity is increased by modifying its surface structure to resemble that of a toxin molecule. In a unique system, native beta-sheet scorpion toxins have been reported to activate skeletal muscle ryanodine receptor calcium channels with high affinity by binding to the same site as the lower-affinity alpha-helical dihydropyridine receptor segment. We increased the alignment of basic residues in the alpha-helical peptide to mimic the spatial orientation of active residues in the scorpion toxin, with a consequent 2-20-fold increase in the activity of the alpha-helical peptide. We hypothesized that, like the native peptide, the modified peptide and the scorpion toxin may bind to a common site. This was supported by (i) similar changes in ryanodine receptor channel gating induced by the native or modified alpha-helical peptide and the beta-sheet toxin, a 10-100-fold reduction in channel closed time, with a < or = 2-fold increase in open dwell time and (ii) a failure of the toxin to further activate channels activated by the peptides. These results suggest that diverse structural scaffolds can present similar conformational surface properties to target common receptor sites.
- Division of Molecular Bioscience, John Curtin School of Medical Research, Australian National University, P.O. Box 334, Canberra, ACT, 2601, Australia.
Organizational Affiliation:
