Characterization of a recessive-lethal amber suppressor strain of Salmonella typhimurium by in vitro synthesis of T4 lysozyme

The RNA-dependent synthesis of T4 lysozyme in vitro has been used to characterize a recessive-lethal amber suppressor (sup-amber) strain of Salmonella typhimurium. T4 lysozyme is synthesized by 30000 × g supernatant extracts of S. typhimurium in the presence of RNA from Escherichia coli Su^- cells infected with T4B (T4 wild-type). RNA from E. coli Su^- cells infected with T4 lysozyme gene amber mutants directs the synthesis of T4 lysozyme in extracts of sup-amber cells, or in extracts of Su^- cells of E. coli or S. typhimurium supplemented with tRNA from the sup-amber strain.