FIGURE 3.

Structural model of PBP1b GT module (212–398) and close view into the catalytic site depicting the positions of the studied conserved residues in sticks. A, motif 1 (M1) is shown in yellow, motif 2 (M2) is shown in salmon, motif 3 (M3) is shown in cyan, motif 4 (M4) is shown in green, and motif 5 (M5) is shown in magenta. The catalytic Glu²³³ and the Glu²⁹⁰ residues are shown in sticks. B, Phe²³⁷ is part of a hydrophobic cluster. C, interaction between Asp²³⁴ and His²⁴⁰ of motif 1 and Thr²⁶⁷ of motif 2. D, Gln²⁷¹ and Tyr³¹⁰ are within interacting distance of the catalytic Glu²³³. E, positively charged residues within the donor site close to the Glu²⁹⁰ are shown. The figures were generated with the help of the PyMOL software.