Fig. 2: Structural mechanism of continuous catalytic reactions by IiPLR1 based on homodimerization.

a Dimer formation of IiPLR1_NAP_ + PIN. Mol-A is shown as cartoon model, with its NBD and SBD colored in light blue and green cyan, respectively. Mol-B is represented as an electrostatic-surface model, on which blue and red colors represent positive and negative charges, respectively. NADP⁺ and (+)-pinoresinol are shown as sticks and colored in orange and yellow, respectively. b Conformational changes were assessed by comparing monomer structures of IiPLR1_apo (gray) and IiPLR1_NAP (light orange). The NADP⁺ bound to IiPLR1_NAP is colored gray. The β4 loops of IiPLR1_apo and IiPLR1_NAP are highlighted as purple and green, respectively. c Zoom-in view of the NADPH-binding groove of IiPLR1_NAP. Residues interacting with NADP⁺ are colored cyan. The conserved GXXGXXG motif is indicated. Residue Val46 involved in dimer formation and substrate binding is shown as a ball-and-stick model and colored magenta. Dotted lines denote possible hydrogen bonds. d Structure comparison of IiPLR1_NAP_ + PIN and IiPLR1_NAP. Mol-Bs of IiPLR1_NAP_ + PIN and IiPLR1_NAP, Val46s in IiPLR1_NAP_ + PIN, and IiPLR1_NAP are colored in marine, orange, magenta, and light yellow, respectively. e Zoom-in view of the substrate-binding groove. Residues of Mol-As in IiPLR1_NAP_ + PIN and IiPLR1_NAP are colored green cyan (or light blue) and light yellow, respectively. f Structural comparation of the substrate/product-binding grooves in IiPLR1_NAP_ + PIN, IiPLR1_NAP_-LAR (blue white), and IiPLR1_NAP_-SEC (smudge). The cartoons are generated by PyMOL. g Enzyme assays for wild-type IiPLR1 and its mutants V46A and V46L. Data are mean±s.d. (n = 3 independent experiments). Asterisk * indicates significant difference from the wild-type enzyme (P < 0.05) analyzed by one-way ANOVA with Tukey’s multiple comparisons test. Source data underlying Fig. 2g are provided as a Source Data file.