Primary structure of protein L19 from the large subunit of Escherichia coli ribosomes

Abstract

Protein L19, a component of the E. coli 50S ribosomal subunit implicated in 30S-50S subunit interaction, was sequenced by the dansyl-Edman method. L19 consists of a single polypeptide chain of 114 amino acids giving a calculated MW of 13,002. Peptides obtained from various enzymatic cleavages were isolated on thin-layer peptide maps or by gel filtration. Automated Edman degradation using a liquid phase sequenator was carried out on the whole protein and on a large 58-residue fragment arising from digestion with Staphylococcus aureus protease. Every position in protein L19 was confirmed at least twice. Results of secondary structure estimation and homologies with other E. coli ribosomal protein sequences are presented.