Conditionally lethal ribosomal protein mutants: characterization of a locus required for modification of 50S subunit proteins.

Abstract
Mutagenized P1 bacteriophage were used to transduce a marker (aroE) adjacent to the cluster of ribosomal protein genes located at 72 min on the Escherichia coli chromosome. Linked temperature-sensitive transductants were isolated and characterized. A mutant unable to grow at 44.degree. C was defective in protein synthesis in vivo and in vitro. At the restrictive temperature mutant cells lost all polyribosomes. Analysis of the ribosomal proteins revealed alterations in at least four 50S subunit proteins. The mutation (called rimE1, ribosomal protein modification) mapped between rpsE and aroE. The rimE locus is probably the structural gene for an activity that modifies a selected number of ribosomal proteins.