A protein-nucleic acid crosslink in 30S ribosomes

The data indicate that probably a single 30s ribosomal protein has been crosslinked to the 3′-ribosyl terminus of 16s RNA in intact 30s ribosomes. The crosslink was made by oxidizing the 3′-ribosyl moiety of 16s RNA to a dialdehyde with NaIO₄. One of the aldehyde groups generated in the oxidation reacted with an α- or ε-amino group of an adjacent protein to form a Schiff's base. The Schiff's base was reduced with NaBH₄ to a stable, specific covalent crosslink between the protein and the 16s RNA molecules. The crosslinked protein was tentatively identified as S1 according to the nomenclature of Wittmann et al. (1971), Mol. Gen. Genetics 111, 327.