Surface representation of different domain dispositions in Mur family structures.

<p>Crystal structures of: (A) apo-<i>Pa</i>Mpl, (B) <i>Ec</i>MurC with bound Mg²⁺, (C) <i>Hi</i>MurC bound to substrates UDP-MurNAc-L-Ala (UMA) and AMPPNP (ANP), and metal; and (D) apo-<i>Ec</i>MurF (on slightly smaller scale compared to A–C as more extended conformation). For all proteins, ND is in green, MD is in cyan and CD is in yellow. These examples illustrate the conformational variability of these Mur enzymes. All molecules are in the same orientation based on their superimposition on the <i>Pa</i>Mpl MD. The CD of the apo-<i>Pa</i>Mpl is rotated 30° with respect to ND and MD compared to the MurC structure. The <i>Pa</i>Mpl domains may open up during substrate binding and close during catalysis.