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NINJA connects the co-repressor TOPLESS to jasmonate signalling
Laurens Pauwels1, Gemma Fernández Barbero, Jan Geerinck
1Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Technologiepark 927, B-9052 Gent, Belgium.
Jasmonoyl-isoleucine (JA-Ile) plant hormone responses are regulated by the Novel Interactor of JAZ (NINJA) protein. NINJA recruits TOPLESS (TPL) co-repressors, revealing a new mechanism for plant defense and development.
Area of Science:
- Plant Biology
- Molecular Biology
- Genetics
Background:
- Jasmonoyl-isoleucine (JA-Ile) is a crucial plant hormone regulating defense and development.
- MYC2 activates JA-Ile-responsive genes by interacting with jasmonate ZIM-domain (JAZ) repressors.
- JAZ protein degradation triggers JA-Ile-dependent gene expression, but repression mechanisms were unclear.
Purpose of the Study:
- To elucidate the molecular mechanisms by which JAZ proteins repress gene expression.
- To identify novel proteins involved in JA-Ile signaling pathways.
- To understand the role of co-repressors in plant hormone responses.
Main Methods:
- Yeast two-hybrid assays to identify protein interactions.
- Co-immunoprecipitation to confirm protein complex formation.
- Analysis of gene expression in Arabidopsis mutants.
Main Results:
- Arabidopsis JAZ proteins recruit TOPLESS (TPL) and TPL-related proteins (TPRs) via a novel adaptor, NINJA.
- NINJA functions as a transcriptional repressor through a TPL-binding EAR motif.
- Both NINJA and TPL act as negative regulators of JA-Ile responses.
Conclusions:
- TPL proteins serve as general co-repressors in multiple plant signaling pathways.
- NINJA acts as a specific adaptor, linking JAZ repressors to the TPL co-repressor complex.
- This mechanism highlights conserved molecular strategies for regulating plant stress and growth signaling.
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