Fig. 5: The binding mode of BS in WT and in the W574L AtAHAS mutant.

a The interactions of BS with WT AtAHAS (PDB code: 1YBH³⁸). ThDP is degraded to ThAThDP (light brown). b The interactions of BS with the W574L mutant. ThDP is oxidized to ThThDP (light brown). a, b BS is in green and ball and stick representation. The FAD is in yellow and in stick representation. Dashed lines represent hydrogen bonds (black). Grey dashed cylinders represent π–π interactions. Blue dashed cylinders represent hydrophobic interactions. c B-factor plot for the polypeptide and herbicide. An increase in normalized B-factor for the herbicide indicates it is not bound as tightly to the mutant as it is to the WT enzyme (top panel). However, the destabilization is not as profound compared (lower panel) to the normalized B-factors for the two CE structures (i.e., WT and W574L mutants). Blue and red represent WT and mutant enzymes, respectively. Lines and triangles represent polypeptide and inhibitor, respectively. d Superimposition of the WT AtAHAS-BS, W574L-BS, and W574L-CE complexes. The superimposition of the WT AtAHAS-BS and W574L-BS structures shows the rotation of the heterocyclic ring that occurs when W574 is mutated to leucine. The superimposition with W574L-CE (CE represented by thin black sticks) shows that the movement of the heterocyclic ring in the W574L mutant is greater for CE than BS.