title: Jasmonate signalling inArabidopsisinvolves SGT1b-HSP70-HSP90 chaperone complexes.
abstract: Plant hormones play pivotal roles in growth, development and stress responses. Although it is essential to our understanding of hormone signalling, how plants maintain a steady state level of hormone receptors is poorly understood. We show that mutation of theArabidopsis thalianaco-chaperoneSGT1bimpairs responses to the plant hormones jasmonate, auxin and gibberellic acid, but not brassinolide and abscisic acid, and that SGT1b and its homologue SGT1a are involved in maintaining the steady state levels of the F-box proteins COI1 and TIR1, receptors for jasmonate and auxin, respectively. The association of SGT1b with COI1 is direct and is independent of theArabidopsisSKP1 protein, ASK1. We further show that COI1 is a client protein of SGT1b-HSP70-HSP90 chaperone complexes and that the complexes function in hormone signalling by stabilizing the COI1 protein. This study extends the SGT1b-HSP90 client protein list and broadens the functional scope of SGT1b-HSP70-HSP90 chaperone complexes.
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Xue-Cheng
authors.initials: XC
authors.lastname: Zhang
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Yves A
authors.initials: YA
authors.lastname: Millet
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Zhenyu
authors.initials: Z
authors.lastname: Cheng
authors.affiliation: Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Jenifer
authors.initials: J
authors.lastname: Bush
authors.affiliation: Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Ausubel