6brq | pdb_00006brq
Crystal structure of rice ASK1-D3 ubiquitin ligase complex crystal form 3
Structural highlights
Function[MAX2_ORYSJ] Controls tillering by suppressing axillary bud activity. Tiller is a specialized grain-bearing branch that is formed on the unelongated basal internode and grows independently of the mother stem (culm) by means of its own adventitious roots. Is necessary for responses to strigolactones and the establishment of arbuscular mycorrhiza symbiosis in rice. May be involved in the ubiquitin-mediated degradation of specific proteins that activate axillary growth. D3 is crucial for establishing arbuscular mycorrhiza (AM) symbiosis in rice, whereas D14 and D14-LIKE are not. Our results suggest distinct roles for these SL-related components in AM symbiosis. [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] Publication Abstract from PubMedThe strigolactones, a class of plant hormones, regulate many aspects of plant physiology. In the inhibition of shoot branching, the alpha/beta hydrolase D14-which metabolizes strigolactone-interacts with the F-box protein D3 to ubiquitinate and degrade the transcription repressor D53. Despite the fact that multiple modes of interaction between D14 and strigolactone have recently been determined, how the hydrolase functions with D3 to mediate hormone-dependent D53 ubiquitination remains unknown. Here we show that D3 has a C-terminal alpha-helix that can switch between two conformational states. The engaged form of this alpha-helix facilitates the binding of D3 and D14 with a hydrolysed strigolactone intermediate, whereas the dislodged form can recognize unmodified D14 in an open conformation and inhibits its enzymatic activity. The D3 C-terminal alpha-helix enables D14 to recruit D53 in a strigolactone-dependent manner, which in turn activates the hydrolase. By revealing the structural plasticity of the SCF(D3-D14) ubiquitin ligase, our results suggest a mechanism by which the E3 coordinates strigolactone signalling and metabolism. Structural plasticity of D3-D14 ubiquitin ligase in strigolactone signalling.,Shabek N, Ticchiarelli F, Mao H, Hinds TR, Leyser O, Zheng N Nature. 2018 Nov;563(7733):652-656. doi: 10.1038/s41586-018-0743-5. Epub 2018 Nov, 21. PMID:30464344[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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