The RNA thiouridylase MnmA in complex with tRNA was crystallized with and without ATP in three different crystal forms, which may reflect distinct sulfuration-reaction stages.
MnmA catalyzes a sulfuration reaction to synthesize 2-thiouridine at the wobble positions of tRNAGlu, tRNAGln and tRNALys in Escherichia coli. The binary complex of MnmA and tRNAGlu was crystallized in two different crystal forms: forms I and II. Cocrystallization of MnmA–tRNAGlu with ATP yielded form III crystals. The three crystal forms diffracted to 3.1, 3.4 and 3.4 Å resolution, respectively, using synchrotron radiation at SPring-8. These crystals belong to space groups C2, I212121 and C2, with unit-cell parameters a = 225.4, b = 175.8, c = 53.0 Å, β = 101.6°, a = 101.5, b = 108.0, c = 211.2 Å and a = 238.1, b = 102.1, c = 108.2 Å, β = 117.0°, respectively. The asymmetric units of these crystals are expected to contain two, one and two MnmA–tRNAGlu complexes, respectively.