Figure 2. Modeling of Tae2/Dae2 Interactions with PG Substrate.

(A) Cartoon schematic of bacterial peptidoglycan (PG) sacculus (left) and PG chemical structure (right) with glycans (rectangles), peptides (circles), and cross-link position (gray line) shown. Residue positions in PG peptide stem are labeled (1–4) with key variable third position (3*) colored in teal.

(B) Surface representation of Tae2^St ligand docking using a stem peptide substrate. Both mDAP residues in the stem peptide are colored in teal.

(C) Close-up of the Tae2^St active site and docked substrate. The scissile amide bond is between mDAP^a and the adjacent D-ala (position 4), proximal to the active site Cys23 residue.

(D) Surface representation of Dae2^Is ligand docking, using the same substrate as for Tae2^St in (C).

(E) Close-up of the Dae2^Is active site and docked substrate. The scissile bond is similarly situated between mDAP^a and the adjacent D-ala, proximal to the active site Cys43 residue. The substrate directionality being mDAP^b – D-ala – mDAP^a is the inverse of that for Tae2^St, mDAP^a – D-ala – mDAP^b.

(F) Consurf server analyses of Tae2^St and Dae2^Is with highly conserved residues shown in red and least conserved in gray. The docked PG substrate is shown.

See also Figures S3 and S4.