2p1n

From Proteopedia

Mechanism of Auxin Perception by the TIR1 Ubiqutin Ligase

Structural highlights

2p1n is a 6 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.5Å
Ligands:	CFA, IHP
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

SKP1A_ARATH Involved in ubiquitination and subsequent proteasomal degradation of target proteins. Together with CUL1, RBX1 and a F-box protein, it forms a SCF E3 ubiquitin ligase complex. The functional specificity of this complex depends of the type of F-box protein. In the SCF complex, it serves as an adapter that links the F-box protein to CUL1. SCF(UFO) is required for vegetative and floral organ development as well as for male gametogenesis. SCF(TIR1) is involved in auxin signaling pathway. SCF(COI1) regulates responses to jasmonates. SCF(EID1) and SCF(AFR) are implicated in phytochrome A light signaling. SCF(ADO1), SCF(ADO2), SCF(ADO3) are related to the circadian clock. SCF(ORE9) seems to be involved in senescence. SCF(EBF1/EBF2) may regulate ethylene signaling. Plays a role during embryogenesis and early postembryonic development, especially during cell elongation and division. Contributes to the correct chromosome segregation during tetrad formation.^[1] ^[2] ^[3] ^[4] ^[5] ^[6]

Evolutionary Conservation

Checkto colour the structure by Evolutionary Conservation, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

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 TIR1 F-box protein senses and becomes activated by auxin remains unclear. Here we present the crystal structures of the Arabidopsis TIR1-ASK1 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 TIR1 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 TIR1 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 TIR1 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.

Mechanism of auxin perception by the TIR1 ubiquitin ligase.,Tan X, Calderon-Villalobos LI, Sharon M, Zheng C, Robinson CV, Estelle M, Zheng N Nature. 2007 Apr 5;446(7136):640-5. PMID:17410169^[7]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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Citations

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References

↑ Zhao D, Yang M, Solava J, Ma H. The ASK1 gene regulates development and interacts with the UFO gene to control floral organ identity in Arabidopsis. Dev Genet. 1999 Sep;25(3):209-23. PMID:10528262 doi:<209::AID-DVG4>3.0.CO;2-O 10.1002/(SICI)1520-6408(1999)25:3<209::AID-DVG4>3.0.CO;2-O
↑ Gray WM, del Pozo JC, Walker L, Hobbie L, Risseeuw E, Banks T, Crosby WL, Yang M, Ma H, Estelle M. Identification of an SCF ubiquitin-ligase complex required for auxin response in Arabidopsis thaliana. Genes Dev. 1999 Jul 1;13(13):1678-91. PMID:10398681
↑ Yang M, Hu Y, Lodhi M, McCombie WR, Ma H. The Arabidopsis SKP1-LIKE1 gene is essential for male meiosis and may control homologue separation. Proc Natl Acad Sci U S A. 1999 Sep 28;96(20):11416-21. PMID:10500191
↑ Zhao D, Yu Q, Chen M, Ma H. The ASK1 gene regulates B function gene expression in cooperation with UFO and LEAFY in Arabidopsis. Development. 2001 Jul;128(14):2735-46. PMID:11526079
↑ Zhao D, Ni W, Feng B, Han T, Petrasek MG, Ma H. Members of the Arabidopsis-SKP1-like gene family exhibit a variety of expression patterns and may play diverse roles in Arabidopsis. Plant Physiol. 2003 Sep;133(1):203-17. PMID:12970487
↑ Liu F, Ni W, Griffith ME, Huang Z, Chang C, Peng W, Ma H, Xie D. The ASK1 and ASK2 genes are essential for Arabidopsis early development. Plant Cell. 2004 Jan;16(1):5-20. Epub 2003 Dec 19. PMID:14688296 doi:10.1105/tpc.017772
↑ Tan X, Calderon-Villalobos LI, Sharon M, Zheng C, Robinson CV, Estelle M, Zheng N. Mechanism of auxin perception by the TIR1 ubiquitin ligase. Nature. 2007 Apr 5;446(7136):640-5. PMID:17410169 doi:10.1038/nature05731