The JAZ family of repressors is the missing link in jasmonate signalling.
Jasmonates are essential phytohormones for plant development and survival. However, the molecular details of their signalling pathway remain largely unknown. The identification more than a decade ago of COI1 as an F-box protein suggested the existence of a repressor of jasmonate responses that is targeted by the SCF(COI1) complex for proteasome degradation in response to jasmonate. Here we report the identification of JASMONATE-INSENSITIVE 3 (JAI3) and a family of related proteins named JAZ (jasmonate ZIM-domain), in Arabidopsis thaliana. Our results demonstrate that JAI3 and other JAZs are direct targets of the SCF(COI1) E3 ubiquitin ligase and jasmonate treatment induces their proteasome degradation. Moreover, JAI3 negatively regulates the key transcriptional activator of jasmonate responses, MYC2. The JAZ family therefore represents the molecular link between the two previously known steps in the jasmonate pathway. Furthermore, we demonstrate the existence of a regulatory feed-back loop involving MYC2 and JAZ proteins, which provides a mechanistic explanation for the pulsed response to jasmonate and the subsequent desensitization of the cell.
Chini
A
A
Departamento de Genética Molecular de Plantas, Centro Nacional de Biotecnología-CSIC, Campus Universidad Autónoma, 28049 Madrid, Spain.
Fonseca
S
S
Fernández
G
G
Adie
B
B
Chico
J M
JM
Lorenzo
O
O
García-Casado
G
G
López-Vidriero
I
I
Lozano
F M
FM
Ponce
M R
MR
Micol
J L
JL
Solano
R
R
D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D003517:Cyclopentanes / Q000494:pharmacology*; D025461:Feedback, Physiological; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005810:Multigene Family; D054883:Oxylipins; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects
D029681:Arabidopsis Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003517:Cyclopentanes; C522646:JAI3 protein, Arabidopsis; C473611:MYC2 protein, Arabidopsis; D054883:Oxylipins; D012097:Repressor Proteins; C011006:jasmonic acid; D044843:SKP Cullin F-Box Protein Ligases; D046988:Proteasome Endopeptidase Complex