3W06: Crystal Structure of Arabidopsis Thaliana Dwarf14 Like (Atd14l)

Strigolactones (SLs) are plant hormones that inhibit shoot branching. DWARF14 (D14) inhibits rice tillering and is an SL receptor candidate in the branching inhibition pathway, whereas the close homologue DWARF14-LIKE (D14L) participates in the signaling pathway of karrikins (KARs), which are derived from burnt vegetation as smoke stimulants of seed germination. We provide the first evidence for direct binding of the bioactive SL analogue GR24 to D14. Isothermal titration calorimetry measurements show a D14-GR24 binding affinity in the sub-micromolar range. Similarly, bioactive KAR1 directly binds D14L in the micromolar range. The crystal structure of rice D14 shows a compact alpha-/beta-fold hydrolase domain forming a deep ligand-binding pocket capable of accommodating GR24. Insertion of four alpha-helices between beta6 strand and alphaD helix forms the helical cap of the pocket, although the pocket is open to the solvent. The pocket contains the conserved catalytic triad Ser-His-Asp aligned with the oxyanion hole, suggesting hydrolase activity. Although these structural characteristics are conserved in D14L, the D14L pocket is smaller than that of D14. The KAR-insensitive mutation kai2-1 is located at the prominent long beta6-alphaD1 loop, which is characteristic in D14 and D14L, but not in related alpha-/beta-fold hydrolases.
PDB ID: 3W06Download
MMDB ID: 106851
PDB Deposition Date: 2012/10/19
Updated in MMDB: 2013/02
Experimental Method:
x-ray diffraction
Resolution: 1.15  Å
Source Organism:
Similar Structures:
Biological Unit for 3W06: monomeric; determined by author and by software (PISA)
Molecular Components in 3W06
Label Count Molecule
Protein (1 molecule)
Hydrolase, Alpha/beta Fold Family Protein(Gene symbol: KAI2)
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB