Figure 4.

Contact frequency (to the P4 residue of substrate peptides) for residues in Cd-SrtB_ΔN26. Cd-SrtB_ΔN26 are shown in surface representation and opaque for the cases of Cd-SrtB_ΔN26–PPKTG (upper-left), Cd-SrtB_ΔN26–SPKTG (upper-right), Cd-SrtB_ΔN26–NPKTG (lower-left) and Cd-SrtB_ΔN26–NVQTG (lower-right). Different peptides are shown as black line, with the P4 residue labeled by ball-and-stick in CPK. The increased contact frequency for the P4 residues in different peptides is colored from blue to red for the purpose of easier visualization.