Fig. 3. Comparison of PCP₂ and PCP₃ domains from fuscachelin biosynthesis.

a Structural alignment of PCP₂ and PCP₃ domains (RMSD 2 Å). b Crystal structure of the PCP₃ domain (PDB ID 7KW3) showing the position of side chains for interaction with C-domain based on PCP₂. c Crystal structure of the PCP₂ domain showing side chains interacting with the C-domain. d Sequence alignment of both PCP₂ and PCP₃ domains with the C domain interface indicated by orange blocks (conserved residues highlighted in red, similar residues shown in red text); site of posttranslational modification highlighted in green.