title: Temporal order of RNA-processing reactions in trypanosomes: rapid trans splicing precedes polyadenylation of newly synthesized tubulin transcripts.
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.
authors.affiliation: Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06510-8056.
authors.forename: E
authors.initials: E
authors.lastname: Ullu
authors.forename: K R
authors.initials: KR
authors.lastname: Matthews
authors.forename: C
authors.initials: C
authors.lastname: Tschudi
mesh_terms: D000818:Animals; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D009694:Nucleic Acid Precursors / Q000378:metabolism; D011061:Poly A / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D016053:RNA, Protozoan / Q000235:genetics*; D013997:Time Factors; D014346:Trypanosoma brucei brucei / Q000235:genetics*; D014404:Tubulin / Q000235:genetics*
chemical_list: D009694:Nucleic Acid Precursors; D012333:RNA, Messenger; D016053:RNA, Protozoan; D014404:Tubulin; D011061:Poly A