Sequential and structural properties of the potential active site of Tse3. (a) Three conserved motifs identified from structure-based sequence alignment between Tse3 and other muramidases containing an SLT domain. Amino-acid conservation is depicted using WebLogo (Crooks et al., 2004). (b) Stereoview of structural superimposition of MltE (PDB entry 2y8p
; purple) and gLYS (PDB entry 3gxr
; green) onto Tse3 (cyan). The invariant residues are highlighted as stick models with element colour indices. (c)–(e) Electrostatic potential maps calculated on the surface of Tse3 including the three calcium ions (c), MltE (d) and gLYS (e). Positive and negative charges are shown in blue and red colours, respectively. The substrate-binding groove in Tse3 is indicated by a black arrow, while those in the other structures are indicated by bound glycan.