Crystallization and preliminary X-ray crystallographic analysis of tRNA(m¹G37)methyltransferase from Haemophilus influenzae

The enzyme tRNA(m¹G37)methyltransferase (TrmD) catalyzes the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet) specifically to guanosine at position 37 within a subset of tRNA species in bacteria. The modified guanosine is next to the anticodon and is important for the maintenance of the correct reading frame during translation. TrmD from Haemophilus influenzae with both N- and C-terminal tags was overexpressed in Escherichia coli and crystallized at 297 K using sodium acetate as a precipitant. Native X-­ray diffraction data were collected to 1.85 Å resolution. The crystals are rhombohedral, belonging to the space group R32, with unit-cell parameters a = b = 98.05, c = 176.79 Å, α = β = 90, γ = 120°. The presence of one monomer of recombinant TrmD in the crystallographic asymmetric unit gives a V_M of 3.07 ų Da⁻¹ and a solvent content of 59.9%.