Cloning and characterization of a Leishmania gene encoding a RNA spliced leader sequence. Nucleic Acids Res

Recent studies on Leishmania enr1ett11 tubulin mRNAs revealed a 35 nucleotide addition to their 51 end. The gene that codes for this 35 nucleotide leader sequence has now been cloned and sequenced. In the Leishmania genome, the spliced leader gene exists as a tandem repeat of 438 bases. There are approximately 150 copies of this gene comprising 0.1 % of the parasite genome. This gene codes for a 85 nucleotide transcript that contains the spliced leader at Its 5 ' end. The 35 nucleotide sequence and the regions immediately 5 ' and 3 ' to 1t are highly conserved across trypanosomatids. We have detected a RNA molecule that 1s a putative by-product of the processing reaction 1n which the 35 nucleotide spliced leader has been transferred to mRNA. We suggest that this molecule 1s the remnant of the spliced leader transcript after removal of the 35 nucleotide spliced leader