A new mutation affecting ribosomal RNA synthesis in Escherichia coli.

A temperature-sensitive mutant of Escherichia coli is described. At the nonpermissive temperature there is a 12-fold reduction in the rate of rRNA synthesis, while tRNA and mRNA syntheses are affected to only a slight extent. Both protein and DNA syntheses also continue at nearly the normal rate. The mutation appears to affect the synthesis of 16S and 23S rRNA equally and has no detectable affect on rRNA maturation. The temperature-sensitive lesion appears to be caused by a single point mutation lying between minutes 21 and 27. It is suggested that this mutation seems to define a new genetic locus involved in the regulation of rRNA synthesis.