Ribonuclease E Is Involved in the Processing of 5‐S rRNA from a Number of rRNA Transcription Units

Strains of Escherichia coli having a thermosensitive RNase E produce a number of 5‐S ribosomal RNA precursors at a non‐permissive temperature. One of these precursors, 9‐S RNA, was reported earlier [Ghora, B. K. and Apirion, D. (1978) Cell, 15, 1055 – 10661. Here we show the existence of additional precursors to 5‐S rRNA, originating from a number of rRNA genes. All the precursors are very similar in the first 200 nucleotides and the last part of this sequence contains the mature 5‐S rRNA. Precursors that contain only these nucleotides (8‐S RNA) accumulate. They probably originate from the rrn genes C, D and F which contain trailer tRNAs. The 9‐S RNA precursors contain in addition a termination stem and loop structure and are derived from genes which do not contain trailer tRNA (Singh and Apirion, unpublished results). In addition, a 10‐S precursor was identified. It contains distal to the 5‐S rRNA a trailer tRNA, tRNAAsp, and a transcription termination signal. It is derived from the rrnF gene. The accumulation of an RNA precursor containing an RNase P site in an rne mutant suggests that the efficiency of one RNA processing enzyme depends on the activity of other RNA processing enzymes.