Characterization of RNA transcripts from the alpha tubulin gene cluster of Leptomonas seymouri.

A tandem cluster of alpha tubulin genes was identified in the trypanosomatid protozoan Leptomonas seymouri. One repeat unit and the first gene of the cluster, with its upstream flanking region, were cloned and analyzed for their transcriptional and coding capacities. The 12-15 copies per cell of the 4 kb repeat encode a stable 2 kb transcript, which contains a mini-exon at its 5' end and two closely spaced polyadenylation sites. Transcription of the alpha tubulin gene cluster in isolated nuclei was unidirectional. Intergenic and coding regions were transcribed at the same rate, and nascent intergenic and coding region transcripts were quantitatively linked. These results are consistent with the possibility that the primary transcripts are polycistronic, or that there is a single small intercistronic gap.