Mechanism of auxin perception by the TIR1 Ubiquitin Ligase  

Oleh:

Tan, Xu ; Calderon-Villalobos, Luz Irina A ; Sharon, Michal ; Zheng, Changxue ; Robinson, Carol V. ; Estelle, Mark ; Zheng, Ning

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: NATURE (keterangan: ada di Proquest) vol. 446 no. 7136 (Apr. 2007), page 640.

Ketersediaan

Perpustakaan FK Nomor Panggil: N01.K.2007.04 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

Lihat Detail Induk

Isi artikel

Auxin is a pivotal plant hormone that controls many aspects of plant growth and development. Perceived by a small family of F-box proteins including transport inhibitor response 1 (TIR1), auxin regulates gene expression by promoting SCF ubiquitin-ligase-catalysed degradation of the Aux/IAA transcription repressors, but how the TIRl F-box protein senses and becomes activated by auxin remains unclear. Here we present the crystal structures of the Arabidopsis TIR1-ASKl complex, free and in complexes with three different auxin compounds and an Aux/IAA substrate peptide. These structures show that the leucine-rich repeat domain of TIRl contains an unexpected inositol hexakisphosphate co-factor and recognizes auxin and the Aux/IAA polypeptide substrate through a single surface pocket. Anchored to the base of the TIRl pocket, auxin binds to a partially promiscuous site, which can also accommodate various auxin analogues. Docked on top of auxin, the Aux/IAA substrate peptide occupies the rest of the TIRl pocket and completely encloses the hormone-binding site. By filling in a hydrophobic cavity at the protein interface, auxin enhances the TIR1-substrate interactions by acting as a 'molecular glue', Our results establish the first structural model of a plant hormone receptor.

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