Root membrane ubiquitinome under osmotic stress reveals specific post-translational modification patterns

ABSTRACT: Osmotic stress is detrimental for the plant which survival relies heavily on proteomic plasticity. Protein ubiquitination is a central post-translational modification (PTM) in osmotic mediated stress. Plants use the ubiquitin proteasome system to modulate protein contents required to respond to and tolerate adverse growth conditions and a role for ubiquitin to mediate endocytosis and trafficking of plant plasma membrane proteins has recently emerged. In this study, using the K-Ɛ-GG antibody enrichment method integrated with high-resolution mass spectrometry, a list of 786 ubiquitinated lysine (K-Ub) residues in 451 proteins of which 50 % were transmembrane proteins was compiled for Arabidopsis root membrane proteins, increasing the database of ubiquitinated substrates in plants. Such analysis allowed to evidence specific ubiquitination motifs, a role for ubiquitination in the internalization and sorting of cargo proteins and ubiquitination dialog with other post-translational modifications (PTMs). In silico interactomics analysis allowed to pinpoint two E2 ligases, UBC32 and UBC34 targeting membrane proteins and putatively involved in response to osmotic stress. The simultaneous quantification of proteome and ubiquitinome after plant treatment with mannitol, suggested a minor role for ubiquitination in protein degradation. Then, this study revealed that a major plasma membrane aquaporin (PIP2;1) harbors two ubiquitination sites that dialog with N-terminal acetylation and C-terminal phosphorylation, to putatively limit PIP2;1 degradation and to favor its internalization contributing to a decreased root hydraulic conductivity (Lpr) while maintaining its cellular abundance.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Root

SUBMITTER: sonia hem  

LAB HEAD: santoni veronique

PROVIDER: PXD022249 | Pride | 2022-04-04

REPOSITORIES: Pride