Figure 4.

Proposed binding sites for HQT1, HQT2, and HCT. Views of the comparative three-dimensional models of HQT1 (A), HQT2 (B), and HCT (C) highlighting the proposed binding sites are shown. α-Helices and β-sheets are shown in gray cartoon representation. The substrates caffeoylquinate (A), p-coumaroylquinate (B), and caffeoylshikimate (C) are shown in stick representation using the PyMOL color code: cyan, carbon atoms; red, oxygen atoms; white, hydrogen atoms; and blue, nitrogen atoms. Possible interactions between the substrates and residues of the proposed binding sites are indicated by black dashed lines. Residues of the binding sites are in pink cartoon and stick representation for HQT1, in yellow cartoon and stick representation for HQT2, and in green cartoon and stick representation for HCT.