PT  - JOURNAL ARTICLE
AU  - Hannes Vanhaeren
AU  - Ying Chen
AU  - Mattias Vermeersch
AU  - Valerie De Vleeschhauwer
AU  - Geert Persiau
AU  - Dominique Eeckhout
AU  - Geert De Jaeger
AU  - Kris Gevaert
AU  - Dirk Inzé
TI  - The deubiquitinating enzymes UBP12 and UBP13 negatively regulate the activity of the ubiquitin-dependent peptidases DA1, DAR1 and DAR2
AID  - 10.1101/802678
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 802678
4099  - http://biorxiv.org/content/early/2019/10/14/802678.short
4100  - http://biorxiv.org/content/early/2019/10/14/802678.full
AB  - Protein ubiquitination is a very diverse post-translational modification leading to protein degradation or delocalization, or altering protein activity. In Arabidopsis thaliana, two E3 ligases, BIG BROTHER (BB) and DA2, activate the latent peptidases DA1, DAR1 and DAR2 by mono-ubiquitination at multiple sites. Subsequently, these activated peptidases destabilize various positive regulators of growth. Here, we show that two ubiquitin-specific proteases, UBP12 and UBP13, deubiquitinate DA1, DAR1 and DAR2, hence reducing their peptidase activity. Overexpression of UBP12 or UBP13 strongly decreased leaf size and cell area, and resulted in lower ploidy levels. Mutants in which UBP12 and UBP13 were downregulated produced smaller leaves that contained fewer and smaller cells. Remarkably, neither UBP12 nor UBP13 were found to be cleavage substrates of the activated DA1. Our results therefore suggest that UBP12 and UBP13 work upstream of DA1, DAR1 and DAR2 to restrict their protease activity and hence fine-tune plant growth and development.