Figure 3
Crystal structure of the CBM and teichoic acid recognition of CbpL.
(A) Ribbon representation of the overall fold of the CBM. Each choline-binding repeat is colored differently and labeled (R1–R9). Choline moieties attached to the choline-binding sites are represented as capped sticks with C atoms in black. Canonical (CS) and non-canonical (NCS) sites are labeled. (B) Molecular architecture of the canonical choline-binding site with critical residues represented as capped sticks and labeled. (C) Molecular architecture of the non-canonical choline-binding site with critical residues represented as capped sticks and labeled. (D) Electrostatic-potential surface of the crystal structure of CbpLCBM:choline complex with the docked model of three TA units (yellow sticks for C atoms) superimposed. Choline moieties and sulphate molecules from the CbpLCBM:choline complex are depicted as black sticks for comparison purposes. (E) Detailed view of the interactions between two docked TA repeating units (RU1 and RU2, light green sticks and dark green sticks respectively) and the CbpLCBM (pink ribbon). Different sugars composing RU in TA are labeled (1: α-AATGalp, 2: β-Glcp, 3: ribitol-5-P, 4: (6-O-PCho)-β-GalpNAc and 5: (6-O-PCho)-α-GalpNAc). Residues involved in TA stabilization are depicted as capped sticks. Canonical sites (CS) and non-canonical sites (NCS) are labeled and polar interactions represented as dotted lines. (F) Scheme of the TA recognition by CS and NCS in CbpL. Residues involved in TA binding are conserved along the CbpLCBM (labeled).
