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.