title: Gibberellin-mediated proteasome-dependent degradation of the barley DELLA protein SLN1 repressor.
abstract: DELLA proteins are nuclear repressors of plant gibberellin (GA) responses. Here, we investigate the properties of SLN1, a DELLA protein from barley that is destabilized by GA treatment. Using specific inhibitors of proteasome function, we show that proteasome-mediated protein degradation is necessary for GA-mediated destabilization of SLN1. We also show that GA responses, such as the aleurone alpha-amylase response and seedling leaf extension growth, require proteasome-dependent GA-mediated SLN1 destabilization. In further experiments with protein kinase and protein phosphatase inhibitors, we identify two additional signaling steps that are necessary for GA response and for GA-mediated destabilization of SLN1. Thus, GA signaling involves protein phosphorylation and dephosphorylation steps and promotes the derepression of GA responses via proteasome-dependent destabilization of DELLA repressors.
authors.affiliation: John Innes Centre, Colney Lane, Norwich NR4 7UJ, United Kingdom.
authors.forename: Xiangdong
authors.initials: X
authors.lastname: Fu
authors.forename: Donald E
authors.initials: DE
authors.lastname: Richards
authors.forename: Tahar
authors.initials: T
authors.lastname: Ait-Ali
authors.forename: Llewelyn W
authors.initials: LW
authors.lastname: Hynes
authors.forename: Helen
authors.initials: H
authors.lastname: Ougham
authors.forename: Jinrong
authors.initials: J
authors.lastname: Peng
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Harberd
mesh_terms: D000483:Alleles; D007611:Aprotinin / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004790:Enzyme Induction / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005875:Gibberellins / Q000494:pharmacology*; D001467:Hordeum / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D009097:Multienzyme Complexes / Q000378:metabolism*; D009154:Mutation; D019319:Okadaic Acid / Q000494:pharmacology; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D012639:Seeds / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013450:Sulfones / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology; D000516:alpha-Amylases / Q000096:biosynthesis
chemical_list: D004791:Enzyme Inhibitors; D005875:Gibberellins; D009097:Multienzyme Complexes; D010940:Plant Proteins; D013450:Sulfones; D019319:Okadaic Acid; C002010:4-(2-aminoethyl)benzenesulfonylfluoride; D014638:Vanadates; D010664:Phenylmethylsulfonyl Fluoride; D007611:Aprotinin; D000516:alpha-Amylases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex