HIGH-RESOLUTION SOLUTION STRUCTURE OF RIBOSOMAL-PROTEIN L11-C76, A HELICAL PROTEIN WITH A FLEXIBLE LOOP THAT BECOMES STRUCTURED UPON BINDING TO RNA

The structure of the C-terminal RNA recognition domain of ribosomal pr otein L11 has been solved by heteronuclear three-dimensional nuclear m agnetic resonance spectroscopy. Although the structure can be consider ed high resolution in the core, 15 residues between helix alpha(1) and strand beta(1) form an extended, unstructured loop. N-15 transverse r elaxation measurements suggest that the loop is moving on a picosecond -to-nanosecond time scale in the free protein but not in the protein b ound to RNA. Chemical shifts differences between the free protein and the bound protein suggest that the loop as well as the C-terminal end of helix alpha 3 are involved in RNA binding.