A missense mutation in the gene coding for ribosomal protein S17 (rpsQ) leading to ribosomal assembly defectivity in Escherichia coli.

The conditionally lethal mutation, 2861 mis, has been mapped inside the ribosomal protein gene cluster at 72 minutes on the Escherichia coli chromosome and was found to cotransduce at 97% with rpsE (S5). The 2861 mis mutation leads to thermosensitivity and impaired assembly in vivo of 30S ribosomal particles at 42 degrees C. The strain carrying the mutation has an altered S 17 ribosomal protein; the mutational alteration involves a replacement of serine by phenylalanine in protein S 17. Spontaneous reversion to temperature independence can restore the normal assembly in vivo of 30 S ribosomal subunits at 42 degrees C and the normal chromatographical behaviour of the S 17 ribosomal protein in vitro. We conclude therefore that the 2861 mis mutation affects the structural gene for protein S 17 (rpsQ).