Ubiquitin-Mediated Proteasomal Degradation of Oleosins is Involved in Oil Body Mobilization During Post-Germinative Seedling Growth in Arabidopsis - AgroParisTech Accéder directement au contenu
Article Dans Une Revue Plant and Cell Physiology Année : 2015

Ubiquitin-Mediated Proteasomal Degradation of Oleosins is Involved in Oil Body Mobilization During Post-Germinative Seedling Growth in Arabidopsis

Résumé

In oleaginous seeds, lipids-stored in organelles called oil bodies (OBs)-are degraded post-germinatively to provide carbon and energy for seedling growth. To date, little is known about how OB coat proteins, known as oleosins, control OB dynamics during seed germination. Here, we demonstrated that the sequential proteolysis of the five Arabidopsis thaliana oleosins OLE1-OLE5 begins just prior to lipid degradation. Several post-translational modifications (e.g. phosphorylation and ubiquination) of oleosins were concomitant with oleosin degradation. Phosphorylation occurred only on the minor OLE5 and on an 8 kDa proteolytic fragment of OLE2. A combination of immunochemical and proteomic approaches revealed ubiquitination of the four oleosins OLE1-OLE4 at the onset of OB mobilization. Ubiquitination topology was surprisingly complex. OLE1 and OLE2 were modified by three distinct and predominantly exclusive motifs: monoubiquitin, K48-linked diubiquitin (K48Ub2) and K63-linked diubiquitin. Ubiquitinated oleosins may be channeled towards specific degradation pathways according to ubiquitination type. One of these pathways was identified as the ubiquitin-proteasome pathway. A proteasome inhibitor (MG132) reduced oleosin degradation and induced cytosolic accumulation of K48Ub2-oleosin aggregates. These results indicate that K48Ub2-modified oleosins are selectively extracted from OB coat and degraded by the proteasome. Proteasome inhibition also reduced lipid hydrolysis, providing in vivo evidence that oleosin degradation is required for lipid mobilization.

Dates et versions

hal-01536438 , version 1 (11-06-2017)

Identifiants

Citer

Carine Deruyffelaere, Isabelle Bouchez-Mahiout, Halima Morin, Alain Guillot, Martine Miquel, et al.. Ubiquitin-Mediated Proteasomal Degradation of Oleosins is Involved in Oil Body Mobilization During Post-Germinative Seedling Growth in Arabidopsis. Plant and Cell Physiology, 2015, 56 (7), pp.1374-1387. ⟨10.1093/pcp/pcv056⟩. ⟨hal-01536438⟩
160 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More