Covalent attachment of a peptidyl-transfer RNA analog to the 50S subunit of Escherichia coli ribosomes.

The peptidyl-tRNA analog, N-bromo-acetyl-Phenylalanyl-tRNA(Phe) has been prepared. Its binding to the 70S ribosome of E. coli is totally dependent upon polyuridylic acid. The analog becomes covalently attached to the 50S particle. It is associated with only one protein fraction after polyacrylamide-gel separation of total 50S proteins. The analog also reacts with 23S ribosomal RNA or a protein that remains tightly bound to this RNA after treatment with LiCl-urea and sodium dodecyl sulfate. The analog can function as a peptidyl-tRNA for at least one peptide transfer, but it then inhibits further chain elongation. This result strongly suggests that this analog becomes covalently bound at the P-site of the ribosome.