6kn2 | pdb_00006kn2
Structure of single disulfide peptide Czon1107-WT (major conformer)
Structural highlights
FunctionCX07_CONZO Inhibits the human alpha-3-beta-4/CHRNA3-CHRNB4 (IC(50)=15.7 uM) and alpha-7/CHRNA7 (IC(50)=77.2 uM) nicotinic acetylcholine receptor (nAChR) (PubMed:32234761). Incomplete inhibition of responses is observed for both subtypes, indicating a potential non-competitive mode of action (PubMed:32234761).[1] Publication Abstract from PubMedConopeptides are neurotoxic peptides in the venom of marine cone snails and have broad therapeutic potential for managing pain and other conditions. Here, we identified the single-disulfide peptides Czon1107 and Cca1669 from the venoms of Conus zonatus and Conus caracteristicus, respectively. We observed that Czon1107 strongly inhibits the human alpha3beta4 (IC50 15.7 +/- 3.0 muM) and alpha7 (IC50 77.1 +/- 0.05 muM) nicotinic acetylcholine receptor (nAChR) subtypes, but the activity of Cca1669 remains to be identified. Czon1107 acted at a site distinct from the orthosteric receptor site. Solution NMR experiments revealed that Czon1107 exists in equilibrium between conformational states that are the result of a key Ser(4)-Pro(5) cis-trans isomerization. Moreover, we found that the X-Pro amide bonds in the inter-cysteine loop are rigidly constrained to cis conformations. Structure-activity experiments of Czon1107 and its variants at positions P5 and P7 revealed that the conformation around the X-Pro bonds (cis-trans) plays an important role in receptor subtype selectivity. The cis conformation at the Cys(6)-Pro(7) peptide bond was essential for alpha3beta4 nAChR subtype allosteric selectivity. In summary, we have identified an unique single disulfide conopeptide with a non-competitive, potentially allosteric inhibitory mechanism at the nAChRs. The small size and rigidity of the Czon1107 peptide could provide a scaffold for rational drug design strategies for allosteric nAChR modulation. This new paradigm in the "conotoxinomic" structure-function space provides an impetus to screen venom from other Conus species for similar, short bioactive peptides that allosterically modulate ligand-gated receptor function. Structure and allosteric activity of a single disulfide conopeptide from Conus zonatus at human alpha3beta4 and alpha7 nicotinic acetylcholine receptors.,Mohan MK, Abraham N, R P R, Jayaseelan BF, Ragnarsson L, Lewis RJ, Sarma SP J Biol Chem. 2020 Mar 31. pii: RA119.012098. doi: 10.1074/jbc.RA119.012098. PMID:32234761[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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