Proteasome activity profiling uncovers alteration of catalytic β2 and β5 subunits of the stress-induced proteasome during salinity stress in tomato roots

ABSTRACT: The stress proteasome in the animal kingdom facilitates faster conversion of oxidized proteins during stress conditions by incorporating different catalytic β subunits. Plants deal with similar kind of stresses and also carry multiple paralogous genes encoding for each of the three catalytic β subunits. Here we investigated the existence of stress proteasomes upon salt stress in tomato roots. In contrast to Arabidopsis thaliana, tomato has a simplified proteasome gene set with single genes encoding each β subunit except for two genes encoding β2. Using proteasome activity profiling on tomato roots during salt stress we discovered a transient modification of the catalytic subunits of the proteasome coinciding with a loss of viability. This stress-induced proteasome disappears at later time points and coincides with the need to degrade oxidized proteins during salt stress. Subunit-selective proteasome probes and MS analysis of fluorescent 2D gels demonstrated that the stress-induced proteasome is not caused by altered subunit assembly, but involves an increased molecular weight (MW) of both β2 and β5 subunits, and an additional acidic pI shift for β5, whilst β1 remains mostly unchanged. Although the underlying subunit modification is unknown, we can rule out ubiquitination, phosphorylation and glycosylation as underlying molecular mechanisms. This stress-induced proteasome may play an important role in PCD during abiotic stress.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Solanum Lycopersicum

TISSUE(S): Root

SUBMITTER: Farnusch Kaschani  

LAB HEAD: Farnusch Kaschani

PROVIDER: PXD005266 | Pride | 2017-02-22

REPOSITORIES: Pride