PDBsum entry 2mgo

Hormone

PDB id: 2mgo

Contents

Ligands

CYS-TYR-ILE-GLN-ASN-CYS-PRO-LEU-GLY

PDB id:

2mgo

Name:

Hormone

Title:

Nmr solution structure of oxytocin

Structure:

Oxytocin. Chain: a. Engineered: yes

Source:

Synthetic: yes. Other_details: the peptide was chemically synthesized.

NMR struc:

20 models

Authors:

P.J.Harvey,D.J.Craik

Key ref:

J.Koehbach et al. (2013). Oxytocic plant cyclotides as templates for peptide G protein-coupled receptor ligand design. Proc Natl Acad Sci U S A, 110, 21183-21188. PubMed id: 24248349 DOI: 10.1073/pnas.1311183110

Date:

01-Nov-13 Release date: 22-Oct-14

DOI no: 10.1073/pnas.1311183110

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

PubMed id: 24248349

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

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

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.