FIGURE 1.
Deletion of the SRL confers a dominant-lethal phenotype. (A) Wild-type (WT) sequence of 23S rRNA nucleotides 2650–2670 and that of the SRL deletion mutant (ΔSRL), in which nucleotides 2653–2667 (the SRL) were replaced with a GAAA tetraloop. (B) Primer-extension analysis of 23S rRNA from affinity-purified WT and ΔSRL 50S subunits probed with either D, dimethylsulfate, or K, kethoxal. Lanes A and G are sequencing lanes; (−) unmodified subunits. (C) E. coli strains that express either WT or ΔSRL MS2-tagged 50S subunits from plasmid, via a heat-inducible promoter, were grown at 30°C, spotted on plates, and incubated at 30°C or 42°C.
