Alternate <i>trans</i> Splicing in <i>Trypanosoma equiperdum</i>: Implications for Splice Site Selection

Layden, Ronald E.; Eisen, Harvey

doi:10.1128/mcb.8.3.1352-1360.1988

Cited by 19 publications

(1 citation statement)

References 32 publications

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“…The two 2.3-kb cDNAs analyzed do not start exactly at the same position, but both are capped with a miniexon sequence. That the miniexon can be added at several possible locations of the same sequence has already been shown by Layden and Eisen (13). On the basis of the observations by these authors, the 3' splice sites transcript (Cl and C2) were determined and found to be identical to the corresponding one from the expression site (ESAG 6 and 0.7 kb of upstream region).…”

Section: Resultsmentioning

confidence: 65%

Trypanosoma brucei: Enrichment by UV of Intergenic Transcripts from the Variable Surface Glycoprotein Gene Expression Site

Coquelet¹,

Tebabi²,

Pays³

et al. 1989

Molecular and Cellular Biology

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The expression site for the variable surface glycoprotein (VSG) gene AnTat 1.3A of Trypanosoma brucei is 45 kilobases long and encompasses seven expression site-associated genes (ESAGs) (E. Pays, P. Tebabi, A. Pays, H. Coquelet, P. Revelard, D. Salmon, and M. Steinert, Cell 57:835-845, 1989). After UV irradiation, several large transcripts from the putative promoter region were strongly enriched. We report that one such major transcript starts near the poly(A) addition site of the first gene (ESAG 7), spans the intergenic region, and extends to the poly(A) addition site of the second gene (ESAG 6), thus bypassing the normal 3' splice site of the ESAG 6 mRNA. Since this transcript is spliced, we conclude that UV irradiation does not inhibit splicing but stabilizes unstable processing products. This demonstrates that at least some intergenic regions of the VSG gene expression site are continuously transcribed in accordance with a polycistronic transcription model.

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Section: Resultsmentioning

confidence: 65%

Trypanosoma brucei: Enrichment by UV of Intergenic Transcripts from the Variable Surface Glycoprotein Gene Expression Site

Coquelet¹,

Tebabi²,

Pays³

et al. 1989

Molecular and Cellular Biology

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Trypanosoma cruzi glycosomal glyceraldehyde-3-phosphate dehydrogenase does not conform to the ‘hotspot’ topogenic signal model.

et al. 1990

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The genes which encode glycosomal glyceraldehyde‐phosphate dehydrogenase (gGAPDH) of Trypanosoma cruzi are arranged as a tandemly repeated pair on a single chromosome and are identical at the level of nucleotide sequence. They are separated by an intergenic region which contains a 317 base pair sequence with the properties of a retroposon. The genes express a 1.5 kb mRNA and a 38 kd protein. The amino acid sequence contains features characteristic of glycosomal enzymes such as peptide insertions and a C‐terminal extension. However, T. cruzi gGAPDH lacks one of the positively charged ‘hotspot’ motifs which have been proposed as topogenic signals for import into the glycosome, a unique microbody‐like organelle. Molecular modelling of the T. cruzi and T. brucei enzymes suggests that neither structure would fulfil the requirements of the ‘hotspot’ glycosomal import model.

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The promoter for a variant surface glycoprotein gene expression site in Trypanosoma brucei.

et al. 1990

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The variant‐specific surface glycoprotein (VSG) gene 221 of Trypanosoma brucei is transcribed as part of a 60 kb expression site (ES). We have identified the promoter controlling this multigene transcription unit by the use of 221 chromosome‐enriched DNA libraries and VSG gene 221 expression site specific transcripts. The start of transcription was determined by hybridization and RNase protection analysis of nascent RNA. The 5′ ends of the major transcripts coming from the initiation region map at nucleotide sequences that do not strongly resemble rRNA transcriptional starts even though the transcripts are synthesized by an RNA polymerase highly resistant to alpha‐amanitin. The cloned VSG gene 221 ES transcription initiation region promotes high CAT gene expression, when reintroduced by electroporation into T. brucei. We show that the activity of this expression site is controlled at or near transcription initiation in bloodstream trypanosomes. The 221 ES is inactivated without any sequence alteration within 1.4 kb of the transcription start site. This excludes mechanisms of promoter inactivation involving DNA rearrangements in the vicinity of the transcription start site, e.g. promoter inversion or conversion.

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Alternate trans Splicing in Trypanosoma equiperdum: Implications for Splice Site Selection

Cited by 19 publications

References 32 publications

Trypanosoma brucei: Enrichment by UV of Intergenic Transcripts from the Variable Surface Glycoprotein Gene Expression Site

Trypanosoma brucei: Enrichment by UV of Intergenic Transcripts from the Variable Surface Glycoprotein Gene Expression Site

Trypanosoma cruzi glycosomal glyceraldehyde-3-phosphate dehydrogenase does not conform to the ‘hotspot’ topogenic signal model.

The promoter for a variant surface glycoprotein gene expression site in Trypanosoma brucei.

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