Isolation and Characterization of Large Transfer Ribonucleic Acid Precursors from Escherichia COG*

Several transfer RNA precursors which accumulate in a strain of Escherichia coli temperature-sensitive for RNase P have been described. These precursors range from 135 to 690 nucleotides in length. Their tRNA content has been determined by digestion of the precursors to 4 S RNA, followed by Sanger fingerprint analysis of the purified 4 S material. Identification of some of these tRNAs, as well as an estimate of the number of copies of tRNA in each precursor has been achieved. Many of these precursor RNA molecules contain multiple copies of the same tRNA sequence, indicating a tandem arrangement of the corresponding tRNA genes in the E. coli genome.