We have identified in Xanthomonas campestris a novel N-acetylornithine transcarbamylase that replaces ornithine transcarbamylase in the canonic arginine biosynthetic pathway of several Eubacteria. The crystal structures of the protein in the presence and absence of the reaction product, N-acetylcitrulline, were determined. This new family of transcarbamylases lacks the DxxSMG motif that is characteristic of all ornithine transcarbamylases (OTCases) and contains a novel proline-rich loop that forms part of the active site. The specificity for N-acetylornithine is conferred by hydrogen bonding with residues in the proline-rich loop via water molecules and by hydrophobic interactions with residues from the adjacent 80's, 120's, and proline-rich loops. This novel protein structure provides a starting point for rational design of specific analogs that may be useful in combating human and plant pathogens that utilize acetylornithine transcarbamylase rather than ornithine transcarbamylase.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below