title: Stabilization of Arabidopsis DREB2A is required but not sufficient for the induction of target genes under conditions of stress.
abstract: The Arabidopsis thaliana transcription factor DEHYDRATION-RESPONSIVE ELEMENT-BINDING PROTEIN2A (DREB2A) controls the expression of many genes involved in the plant's response to dehydration and heat stress. Despite the significance of post-translational regulation in DREB2A activation, the mechanism underlying this activation remains unclear. Here, with the aid of a newly produced antibody against DREB2A, we characterized the regulation of DREB2A stability in plants exposed to stress stimuli. Endogenous DREB2A accumulated in wild-type Arabidopsis plants subjected to dehydration and heat stress. A degradation assay using Arabidopsis T87 suspension-cultured cells revealed that DREB2A protein degradation was inhibited at high temperatures. The proteasome-dependent degradation of DREB2A required the import of this protein into the nucleus. The E3 ligases DRIP1 and DRIP2 were involved in this process under both normal and stressful conditions; however, other E3 ligases may have also been involved, at least during the late stages of the heat stress response. Although the constitutive expression of DREB2A resulted in an overproduction of DREB2A and enhanced target gene induction during stress in transgenic plants, the accumulation of DREB2A caused by proteasome inhibitors did not induce target gene expression. Thus, the stabilization of DREB2A is important but not sufficient to induce target gene expression; further activation processes are required.
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan ; Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Morimoto
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Mizoi
authors.affiliation: Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Japan.
authors.forename: Feng
authors.initials: F
authors.lastname: Qin
authors.affiliation: Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Korea.
authors.forename: June-Sik
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Sato
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Osakabe
authors.affiliation: RIKEN Center for Sustainable Resource Science, Yokohama, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Shinozaki
authors.affiliation: Laboratory of Plant Molecular Physiology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan ; Biological Resources and Post-Harvest Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Japan.
authors.forename: Kazuko
authors.initials: K
authors.lastname: Yamaguchi-Shinozaki
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003681:Dehydration; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D017343:Genes, Plant; D049452:Green Fluorescent Proteins / Q000378:metabolism; D018869:Heat-Shock Response / Q000187:drug effects / Q000235:genetics; D007976:Leupeptins / Q000494:pharmacology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019913:Nuclear Localization Signals / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors / Q000494:pharmacology; D055550:Protein Stability / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D013696:Temperature; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C114579:DREB2A protein, Arabidopsis; D007976:Leupeptins; D019913:Nuclear Localization Signals; D061988:Proteasome Inhibitors; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde