PT  - JOURNAL ARTICLE
AU  - Chen Liu
AU  - Simon Stael
AU  - Kris Gevaert
AU  - Frank Van Breusegem
AU  - Peter V Bozhkov
AU  - Panagiotis N Moschou
TI  - The Proteolytic Landscape of an Arabidopsis Separase-Deficient Mutant Reveals Novel Substrates Associated With Plant Development
AID  - 10.1101/140962
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 140962
4099  - http://biorxiv.org/content/early/2017/05/24/140962.short
4100  - http://biorxiv.org/content/early/2017/05/24/140962.full
AB  - Digestive proteolysis executed by the proteasome plays an important role in plant development. Yet, the role of limited proteolysis in this process is still obscured due to the absence of studies. Previously, we showed that limited proteolysis by the caspase-related protease separase (EXTRA SPINDLE POLES [ESP]) modulates development in plants through the cleavage of unknown substrates. Here we used a modified version of the positional proteomics method COmbined FRActional DIagonal Chromatography (COFRADIC) to survey the proteolytic landscape of wild-type and separase mutant RADIALLY SWOLLEN 4 (rsw4) root tip cells, as an attempt to identify targets of separase. We have discovered that proteins involved in the establishment of pH homeostasis and sensing, and lipid signalling in wild-type cells, suggesting novel potential roles for separase. We also observed significant accumulation of the protease PRX34 in rsw4 which negatively impacts growth. Furthermore, we observed an increased acetylation of N-termini of rsw4 proteins which usually comprise degrons identified by the ubiquitin-proteasome system, suggesting that separase intersects with additional proteolytic networks. Our results hint to potential pathways by which separase could regulate development suggesting also novel proteolytic functions.