Interaction of fMet-tRNA(fMet) with the C-terminal domain of translationalinitiation factor IF2 from Bacillus stearothermophilus

Analytical ultracentrifugation studies indicated that the C-tcrminal domain s of IF2 comprising amino acid residues 520 741 (IF2 C) and 632-741 (IF2 C- 2) bind fMet-tRNA with similar affinities (k(d) at 25 degrees C equal to 0. 27 and 0.23 mu M, respectively). Complex formation between tMet-tRNA(fmet) and IF2 C or IF2 C-2 is accompanied by barely detectable spectral changes a s demonstrated by a comparison of the Raman spectra of the completes with t he calculated sum of the spectra of the individual components. These result s and the temperature dependence of the lid of the protein-RNA complexes in dicate that complex formation is not accompanied by obvious conformational changes of the components, and possibly depends on a rather small binding s ite comprising only a few interacting residues of both components, (C) 2000 Federation of European Biochemical Societies.