The flexible region of protein L12 from bacterial ribosomes studied by proton nuclear magnetic resonance.

The dimeric protein L7/L12 from bacterial ribosomes has a highly elongated and flexible structure. We have, using 1H NMR methods, analyzed the extent of the flexible region and also the size of the organized structures of the molecule. A number of mutants of the protein as well as monomeric and dimeric forms of the protein and a COOH-terminal fragment have been used for the identification of certain resonances. Thus, residues 37-50 were found to be highly mobile whereas the amino-terminal and COOH-terminal regions are organized into folded domains. The flexibility between the domains and its relation to functional properties of the protein are discussed.