Preliminary characterization by X-ray diffraction and Raman spectroscopy of a crystalline complex of Bacillus stearothermophilus initiation factor 2 C-domain and fMet-tRNA(fMet)

Bacillus stearothermophilus translation initiation factor 2 (IF2) specifica lly binds initiator fMet-tRNA(fMet) and positions it into the ribosomal pep tidyl site in the course of the initiation of protein biosynthesis. The iso lated C-terminal domain of IF2 is capable of binding PMet-tRNA(fMet). as sh own by RNase A and hydrolysis protection experiments. In the presence of fM et-tRNA(fMet), the IF2 C-domain yielded orthorhombic crystals of space grou p I222 (I2(1)2(1)2(1)) diffracting to 3.4 Angstrom resolution. The existenc e of equimolar amounts of tRNA and protein in the crystals was proven bq Ra man spectroscopy. The observed unit cell suggests the presence of two IF2 C -domain-fMet-tRNA(fMet) complexes per asymmetric unit of the crystal.