Expression of the ubiquitin variant ubR48 decreases proteolytic activity in Arabidopsis and induces cell death.
The ubiquitin-proteasome pathway is the major route for protein degradation in eukaryotes. We show here that this pathway can be inhibited in Arabidopsis thaliana by expression of a ubiquitin variant that contains Arg instead of Lys at position 48 (ubR48). A major consequence of ubR48 expression is the induction of cell death. Cell death induction coincides with the appearance of reactive oxygen intermediates, but is independent of salicylic acid. We found changes in expression of some defense-related genes, but these changes are apparently insufficient to cause alterations in the response to a bacterial pathogen. Expression of ubR48 from an inducible gene allowed investigation of kinetic parameters of cell death induction. In the absence of additional stress factors, slow death processes dominate if the transgene is induced in seedlings older than 2 weeks. The inducible gene also allowed isolation of suppressor mutants. Expression of ubR48 may cause changes similar to inhibition of the proteasome, which also induces various forms of cell death. Thus, ubR48 is a tool to manipulate protein turnover and to probe cell death programs in plants.
Schlögelhofer
Peter
P
Institute of Botany, University of Vienna, Austria.
Garzón
Marcus
M
Kerzendorfer
Claudia
C
Nizhynska
Viktoria
V
Bachmair
Andreas
A
D017209:Apoptosis / Q000502:physiology*; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D003517:Cyclopentanes / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics; D007976:Leupeptins / Q000494:pharmacology; D009154:Mutation; D054883:Oxylipins; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000033:anatomy & histology / Q000378:metabolism; D030821:Plants, Genetically Modified; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D020156:Salicylic Acid / Q000494:pharmacology; D036226:Seedlings / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction; D025801:Ubiquitin / Q000235:genetics* / Q000378:metabolism*
D029681:Arabidopsis Proteins; D003517:Cyclopentanes; D007976:Leupeptins; D054883:Oxylipins; D010937:Plant Growth Regulators; D025801:Ubiquitin; C077262:PR-1 protein, Arabidopsis; C011006:jasmonic acid; D003907:Dexamethasone; D046988:Proteasome Endopeptidase Complex; D020156:Salicylic Acid; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde