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. 1993 Jan;13(1):720–725. doi: 10.1128/mcb.13.1.720

Temporal order of RNA-processing reactions in trypanosomes: rapid trans splicing precedes polyadenylation of newly synthesized tubulin transcripts.

E Ullu 1, K R Matthews 1, C Tschudi 1
PMCID: PMC358950  PMID: 8417363

Abstract

Many trypanosome genes are expressed as part of large polycistronic transcription units. This finding suggests that regulation of mRNA biogenesis may emphasize RNA-processing reactions more so than in other organisms. This study was undertaken to understand the temporal order of two RNA-processing reactions, trans splicing and polyadenylation, in the maturation of trypanosome mRNAs in vivo. Kinetic studies revealed rapid trans splicing of alpha-tubulin, beta-tubulin, and actin pre-mRNAs within 1 to 2 min after synthesis of the 3' splice site. Furthermore, following blockage of pre-mRNA synthesis, newly synthesized spliced leader RNA cannot be used for trans splicing, suggesting that trypanosomes do not accumulate substantial amounts of pre-mRNA which can provide splice acceptor sites. Thus, trans splicing is cotranscriptional. In addition, we show that trans splicing precedes polyadenylation in the processing of trypanosome tubulin pre-mRNAs.

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