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  • Title: In vivo transcriptional analysis of the spliced leader RNA gene in the trypanosomatid Leptomonas seymouri.
    Author: Crenshaw-Williams K, Bellofatto V.
    Journal: Parasitol Res; 1999 Aug; 85(8-9):700-6. PubMed ID: 10431736.
    Abstract:
    Gene expression in all organisms requires the direct and indirect interaction of multiple proteins with specific DNA sequence elements. Using the monogenetic trypanosomatid, Leptomonas seymouri, we investigated the cis- and trans-acting components that determine expression of a central trypanosomatid RNA, the spliced leader (SL) RNA. Using base substitution mutagenesis and DNA transfection assays, we determined that the SL RNA gene promoter lies exclusively up-stream from the transcription initiation site. Accordingly, the SL RNA gene can be used as a gene cassette to express short heterologous RNAs of interest. We utilized two pharmacological agents, alpha-amanitin and tagetitoxin, and the detergent sarkosyl to assess components of the trans-acting machinery involved in transcription. The SL RNA inhibition pattern was distinct from that of alpha-tubulin, tRNA or ribosomal RNA. Taken together, these data suggest that the upstream SL RNA gene promoter serves to nucleate a transcriptional complex that is distinct, in either its initiation and/or elongation abilities, from other genes. A comparison of trypanosomatid SL RNA gene promoter structures with that found in the nematode Ascaris lumbricoides underscores a taxonomic difference in promoter architectures which may reflect differential requirements for the SL RNA in these organisms.
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