Figure 2.

Anisotropic coordination of the COI1 solenoid by inositol polyphosphate suggests activation of the jasmonate receptor by an allosteric switch. A to C, Structural snapshots of the COI1-ASK1-JAZ1 degron complex bound to coronatine and different inositol polyphosphates (as indicated) generated from in silico docking experiments. COI1 (gray), JAZ1 degron (dark red), inositol polyphosphates (magenta stick), and coronatine (yellow stick) are presented. Residues employed for mutagenesis and yeast two-hybrid assays are depicted in bold (Arg-346, Lys-492) or orange (His-118) in the 1,5-InsP₈ structure. Bottom views (A) of InsP₅ [3-OH] and 1,X InsP₈ structures, as well as side view (B) and top view (C) of the presumed 1,3-InsP₈ and coronatine binding pockets, are shown. Dashed gray lines represent strong polar contacts; dashed firebrick lines mark a weak polar contact between the side chain of JAZ1 residue Arg-206 and the carboxy group of coronatine. D, JAZ12 interaction with wild-type or mutant COI1 in yeast was evaluated in the presence of 50 μm coronatine by coexpression of pGBKT7-COI1 (and mutated versions as indicated) with pGADT7-JAZ12 in yeast strain Y187 (Clontech) and subsequent quantification of β-galactosidase-mediated hydrolysis of ortho-nitrophenyl-β-d-galactopyranoside. Values represent means of two independent biological replicas ±se. BD+AD, yeast strain harboring the empty vector controls pGBKT7 (expressing the Gal4 DNA-binding domain) and pGADT7 (expressing the Gal4 activation domain).