Solving the structure of Escherichia coli elongation factor Tu using a twinned data set

Escherichia coli elongation factor Tu–GDP (EF‐Tu–GDP) was crystallized in the presence of novel inhibitors. The only crystals which could be grown were epitaxially as well as merohedrally twinned, highly mosaic and diffracted to a resolution of 3.4 Å in space group P3121, with unit‐cell parameters a = b = 69.55, c = 169.44 Å, α = β = 90, γ = 120°. To determine whether an inhibitor was present in the crystal, a poor‐quality X‐ray diffraction data set had to be processed. The three‐dimensional structure was ultimately solved and the original question answered. The results also reveal a new type of dimer packing for EF‐Tu–GDP.