3 MUTANT L7 L12 RIBOSOMAL-PROTEINS

Three mutant L7/L12 ribosomal proteins with Ser1, Met14, or Met126 rep laced by Tyr were obtained for studying the structure of N-terminal do main of the protein. Point mutations in the L7/L12 gene were generated with the aid of phage M13mp18. Recombinant plasmids containing the mu tated genes were constructed by using expression vector pKK223-3 and t he pUC19 plasmid. Mutant proteins were expressed in Escherichia coli c ells; purification methods for these proteins were elaborated. It was demonstrated that the structure and general features of the mutant pro teins were virtually identical to the wild-type L7/L12 protein; thus, they were suitable for an H-1-NMR study of the latter. The mutant prot eins were able to bind to E. coIi ribosomes.