A minimal ribosomal RNA: sequence and secondary structure of the 9S kinetoplast ribosomal RNA from Leishmania tarentolae

The portion of the Leishmania tarentolae kinetoplast maxicircle DNA encoding the 9S RNA gene was sequenced, and the 5′and 3′ends of the transcript were determined. A secondary structure for the 9S RNA was determined based on the Escherichia coli 16S model. The 610-nucleotide 9S RNA exhibits a minimal secondary structure in which all four domains of the E. coli 16S structure are preserved. Within domains, however, some stems and loops have been greatly reduced or eliminated entirely. It is presumed that these reduced domains represent the minimal essential small ribosomal RNA secondary structures necessary for a functional ribosome. Alignment of the L. tarentolae 9S rRNA sequence with the published Trypanosoma brucei 9S rRNA sequence shows a nucleotide similarity of 84% and a transversion/transition ratio of 1.66.