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Nat Chem Biol. 2009 May;5(5):344-50. doi: 10.1038/nchembio.161. Epub 2009 Apr 6.

(+)-7-iso-Jasmonoyl-L-isoleucine is the endogenous bioactive jasmonate.

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1
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma, Madrid, Spain.

Abstract

Hormone-triggered activation of the jasmonate signaling pathway in Arabidopsis thaliana requires SCF(COI1)-mediated proteasome degradation of JAZ repressors. (-)-JA-L-Ile is the proposed bioactive hormone, and SCF(COI1) is its likely receptor. We found that the biological activity of (-)-JA-L-Ile is unexpectedly low compared to coronatine and the synthetic isomer (+)-JA-L-Ile, which suggests that the stereochemical orientation of the cyclopentanone-ring side chains greatly affects receptor binding. Detailed GC-MS and HPLC analyses showed that the (-)-JA-L-Ile preparations currently used in ligand binding studies contain small amounts of the C7 epimer (+)-7-iso-JA-L-Ile. Purification of each of these molecules demonstrated that pure (-)-JA-L-Ile is inactive and that the active hormone is (+)-7-iso-JA-L-Ile, which is also structurally more similar to coronatine. In addition, we show that pH changes promote conversion of (+)-7-iso-JA-L-Ile to the inactive (-)-JA-L-Ile form, thus providing a simple mechanism that can regulate hormone activity through epimerization.

PMID:
19349968
DOI:
10.1038/nchembio.161
[Indexed for MEDLINE]
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