Origin of 16S and 23S rRNAs and the E. coli str operon, as derived from tandem tRNA repeats.

The bases 1175-1542 (3'-term.) and 94-510 of the E. coli (EC) 16S rRNA are both homologous to the [5S rRNA-tRNA Asn-tRNA(Ser)-tRNA(Glu)-tRNA(Val)-tRNA(Met)] region of the Bacillus subtilis (BSU) trrnD operon, and to the S12 and S7 r-protein-encoding region (S12/S7 region) in the EC str operon. The 2570-2906 (3'-term.) of the EC 23S rRNA is also homologous to the trrnD. These rRNAs had evolved from a str-like pre-mRNA.