2MGO

NMR solution structure of oxytocin

PDB DOI: https://doi.org/10.2210/pdb2MGO/pdb
BMRB: 19595

Classification: HORMONE
Mutation(s): No

Deposited: 2013-11-01 Released: 2014-10-22
Deposition Author(s): Harvey, P.J., Craik, D.J.

Experimental Data Snapshot

Method: SOLUTION NMR
Conformers Calculated: 50
Conformers Submitted: 20
Selection Criteria: structures with the lowest energy

wwPDB Validation 3D Report Full Report

This is version 1.1 of the entry. See complete history.

Literature

Oxytocic plant cyclotides as templates for peptide G protein-coupled receptor ligand design.

Koehbach, J., O'Brien, M., Muttenthaler, M., Miazzo, M., Akcan, M., Elliott, A.G., Daly, N.L., Harvey, P.J., Arrowsmith, S., Gunasekera, S., Smith, T.J., Wray, S., Goransson, U., Dawson, P.E., Craik, D.J., Freissmuth, M., Gruber, C.W.

(2013) Proc Natl Acad Sci U S A 110: 21183-21188

PubMed: 24248349 Search on PubMedSearch on PubMed Central
DOI: https://doi.org/10.1073/pnas.1311183110
Primary Citation of Related Structures:
2MGO, 2RU2

PubMed Abstract:
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 V1a 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.