Crystallization and preliminary X-ray analysis of the Escherichia coli UDP-MurNAc-tripeptide D-alanyl-D-alanine-adding enzyme (MurF)

Crystals of the Escherichia coli UDP-MurNAc-tripeptide D-Ala-D-Ala-adding protein (MurF), which catalyzes the formation of the last metabolite of the bacterial cell-wall building block, have been grown in hanging-drop vapor-diffusion trials using PEG 8K as a precipitating agent. The crystals belong to hexagonal space group P6₁ or P6₅, with unit-cell dimensions a = b = 74, c = 425 Å. The asymmetric unit contains two molecules, with a crystal volume per protein mass (V_m) of 3.4 Å³ Da^-1 and a solvent content of about 64% by volume. A native data set to 2.8 Å resolution has been obtained from a frozen crystal using a synchrotron X-ray source.