Effects of essential amino acid starvation in Streptococcus faecalis: structural change in the 50S ribosomal subunit.

The 50S ribosomal subunits obtained from exponential-phase and valine-limited cultures of Streptococcus faecalis 9790 differed in protein content. Approximately 35% of the valine-limited subunits showed protein losses when analyzed by CsCl density centrifugation after formaldehyde fixation. Results of density gradient analysis and of acrylamide gel electrophoresis localized the protein to a "split" subunit fraction. No differences could be detected in the protein contents of 30S subunits from exponential-phase and valine-limited cultures.