Crystallization and preliminary X-ray characterization of queD from Bacillus subtilis, an enzyme involved in queuosine biosynthesis.

QueD (previously named ykvK) is one of several enzymes involved in the biosynthesis of the hypermodified nucleoside queuosine. Queuosine is incorporated into tRNA at position 34 of four tRNAs: tRNA(His), tRNA(Asp), tRNA(Asn) and tRNA(Tyr). The crystallization and preliminary X-ray crystallographic studies of queD are described here. The recombinant protein from Bacillus subtilis was overproduced in Escherichia coli and crystallized using the hanging-drop vapor-diffusion method from 25% PEG 600, 100 mM NaCl and sodium citrate buffer pH 5.5 at 291 K. The crystals diffract to 3.6 A resolution and belong to the cubic space group F4(1)32, with unit-cell parameter a = 240.88 A.