Peer-Reviewed Journal Details
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Koehbach, J,O'Brien, M,Muttenthaler, M,Miazzo, M,Akcan, M,Elliott, AG,Daly, NL,Harvey, PJ,Arrowsmith, S,Gunasekera, S,Smith, TJ,Wray, S,Goransson, U,Dawson, PE,Craik, DJ,Freissmuth, M,Gruber, CW
2013
December
Proceedings Of The National Academy Of Sciences Of The United States Of America
Oxytocic plant cyclotides as templates for peptide G protein-coupled receptor ligand design
Published
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Optional Fields
circular plant peptide peptide ligand design uterotonic chemical pharmacology peptide drugs CYCLIC-CYSTINE-KNOT KALATA B1 UTERINE CONTRACTILITY HUMAN MYOMETRIUM DRUG DESIGN VASOPRESSIN ANTAGONISTS BINDING AGONIST MECHANISM
110
52
21183
21188
Cyclotides are plant peptides comprising a circular backbone and three conserved disulfide bonds that confer them with exceptional stability. They were originally discovered in Oldenlandia affinis based on their use in traditional African medicine to accelerate labor. Recently, cyclotides have been identified in numerous plant species of the coffee, violet, cucurbit, pea, potato, and grass families. Their unique structural topology, high stability, and tolerance to sequence variation make them promising templates for the development of peptide-based pharmaceuticals. However, the mechanisms underlying their biological activities remain largely unknown; specifically, a receptor for a native cyclotide has not been reported hitherto. Using bioactivity-guided fractionation of an herbal peptide extract known to indigenous healers as "kalata-kalata," the cyclotide kalata B7 was found to induce strong contractility on human uterine smooth muscle cells. Radioligand displacement and second messenger-based reporter assays confirmed the oxytocin and vasopressin V-1a receptors, members of the G protein-coupled receptor family, as molecular targets for this cyclotide. Furthermore, we show that cyclotides can serve as templates for the design of selective G protein-coupled receptor ligands by generating an oxytocin-like peptide with nanomolar affinity. This nonapeptide elicited dose-dependent contractions on human myometrium. These observations provide a proof of concept for the development of cyclotide-based peptide ligands.
DOI 10.1073/pnas.1311183110
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