title: 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 abiotic stress (salt stress) in tomato roots. In contrast toArabidopsis 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 cell viability. This stress-induced active 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 detected stress-induced proteasome is not caused by an altered composition of subunits in active proteasomes, but involves an increased molecular weight of both labeled β2 and β5 subunits, and an additional acidic pI shift for labeled β5, whilst labeled β1 remains mostly unchanged. Treatment with phosphatase or glycosidases did not affect the migration pattern. This stress-induced proteasome may play an important role in PCD during abiotic stress.
authors.affiliation: Department of Plant Biology, University of Szeged Szeged, Hungary.
authors.forename: Judit
authors.initials: J
authors.lastname: Kovács
authors.affiliation: Department of Plant Biology, University of Szeged Szeged, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Poór
authors.affiliation: Chemical Biology, Fakultät für Biologie, Zentrum für Medizinische Biotechnologie, Universität Duisburg-Essen Essen, Germany.
authors.forename: Farnusch
authors.initials: F
authors.lastname: Kaschani
authors.affiliation: Plant Chemetics Laboratory, Department of Plant Sciences, University of OxfordOxford, UK; Plant Chemetics Laboratory, Max Planck Institute for Plant Breeding ResearchCologne, Germany.
authors.forename: Balakumaran
authors.initials: B
authors.lastname: Chandrasekar
authors.affiliation: Plant Chemetics Laboratory, Department of Plant Sciences, University of OxfordOxford, UK; Plant Chemetics Laboratory, Max Planck Institute for Plant Breeding ResearchCologne, Germany.
authors.forename: Tram N
authors.initials: TN
authors.lastname: Hong
authors.affiliation: Plant Chemetics Laboratory, Max Planck Institute for Plant Breeding ResearchCologne, Germany; Botanical Institute and Cluster of Excellence on Plant Sciences, University of CologneCologne, Germany.
authors.forename: Johana C
authors.initials: JC
authors.lastname: Misas-Villamil
authors.affiliation: Leiden Institute of Chemistry, Leiden University Leiden, Netherlands.
authors.forename: Bo T
authors.initials: BT
authors.lastname: Xin
authors.affiliation: Chemical Biology, Fakultät für Biologie, Zentrum für Medizinische Biotechnologie, Universität Duisburg-Essen Essen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Kaiser
authors.affiliation: Leiden Institute of Chemistry, Leiden University Leiden, Netherlands.
authors.forename: Herman S
authors.initials: HS
authors.lastname: Overkleeft
authors.affiliation: Department of Plant Biology, University of Szeged Szeged, Hungary.
authors.forename: Irma
authors.initials: I
authors.lastname: Tari
authors.affiliation: Plant Chemetics Laboratory, Department of Plant Sciences, University of OxfordOxford, UK; Plant Chemetics Laboratory, Max Planck Institute for Plant Breeding ResearchCologne, Germany.
authors.forename: Renier A L
authors.initials: RA
authors.lastname: van der Hoorn
keywords: 20S proteasome; activity-based protein profiling; catalytic subunit; immune proteasome; programmed cell death; salt stress; tomato root