Transient Activity Assays of the <i>Trypanosoma brucei</i> Variant Surface Glycoprotein Gene Promoter: Control of Gene Expression at the Posttranscriptional Level

Jefferies, David; Tebabi, Patricia; Pays, Étienne

doi:10.1128/mcb.11.1.338-343.1991

Cited by 8 publications

(2 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The vsg ES promoter can drive high levels of expression following transient transfection in both bloodstream and procyclic‐form cells (Jefferies et al ., 1991; Zomerdijk et al ., 1991). Levels of activity are similar to those from the rRNA or parp promoters (Zomerdijk et al ., 1991).…”

Section: Discussionmentioning

confidence: 99%

Position-dependent and promoter-specific regulation of gene expression in Trypanosoma brucei

Horn

Cross

1997

The EMBO Journal

View full text Add to dashboard Cite

Trypanosoma brucei evades the mammalian immune response by a process of antigenic variation. This involves mutually exclusive and alternating expression of telomere-proximal variant surface glycoprotein genes (vsgs), which is controlled at the level of transcription. To examine transcription repression in T.brucei we inserted reporter genes, under the control of either rRNA or vsg expression site (ES) promoters, into various chromosomal loci. Position-dependent repression of both promoters was observed in the mammalian stage of the life cycle (bloodstream forms). Repression of promoters inserted into a silent ES was more pronounced closer to the telomere and was bi-directional. Transcription from both ES and rRNA promoters was also efficiently repressed at a non-telomeric vsg locus in bloodstream-form trypanosomes. In cultured tsetse fly midgut-stage (procyclic) trypanosomes, in which vsg is not normally expressed, all inserted rRNA promoters were derepressed but ES promoters remained silent. Our results suggest that vsg promoters and ectopic rRNA promoters in bloodstream-form T.brucei are restrained by position effects related to their proximity to vsgs or other features of the ES. Sequences present in rRNA promoters but absent from vsg ES promoters appear to be responsible for rRNA promoter-specific derepression in procyclic cells.

show abstract

Section: Discussionmentioning

confidence: 99%

Position-dependent and promoter-specific regulation of gene expression in Trypanosoma brucei

Horn

Cross

1997

The EMBO Journal

View full text Add to dashboard Cite

show abstract

“…VSG transcripts are no longer detectable, but PARP transcripts are up-regulated at least 104-fold. There is clearly a strong posttranscriptional contribution to this regulation (17,20), but the nature and extent of transcriptional control (whether of initiation, elongation, or premature termination) are unclear (8,15,26,30). In transient transfection assays using procyclic and bloodstream trypanosomes, the PARP, VSG, and rRNA promoters were found to have similar activities (16a, 17, 48).…”

mentioning

confidence: 99%

The PARP and rRNA Promoters of Trypanosoma brucei Are Composed of Dissimilar Sequence Elements That Are Functionally Interchangeable

Janz¹,

Clayton²

1994

Molecular and Cellular Biology

View full text Add to dashboard Cite

The African trypanosomes express two major surface proteins, the variant surface glycoprotein (VSG) and the procyclic acidic repetitive protein (PARP). The RNA polymerase that transcribes the VSG and PARP genes shares many characteristics with RNA polymerase I. We show that although there is very little similarity in nucleotide sequence, the functional structure of a trypanosome rRNA promoter is almost identical to that of the PARP promoter. Further, domains from the PARP promoter can functionally substitute for the corresponding parts of the rRNA promoter, and vice versa.

show abstract

Active VSG Expression Sites in Trypanosoma brucei Are Depleted of Nucleosomes

2010

View full text Add to dashboard Cite

In eukaryotes nuclear DNA is packaged into linear arrays of nucleosomes, which provides one of the main determinants of accessibility to DNA binding proteins (37,60,68,82). Nucleosomes consist of ϳ146 bp of DNA wrapped around a histone octamer composed of two copies each of histones H2A, H2B, H3, and H4 (44). The ability to change how DNA is packaged within nucleosomes allows variation in the accessibility of different DNA binding sites and permits fine modulation of promoter activity (33). Recently, there have been major advances in our understanding of how chromatin structure impacts the regulation of RNA polymerase II (Pol II) transcription units. New developments (72) have enabled the determination of the global organization of nucleosomes in organisms including budding yeast, Drosophila, and humans (3,35,36,48,71,83). These studies have shown evidence for nucleosome depletion at transcriptionally active regulatory regions, with the level of nucleosome occupancy inversely proportional to the rate of transcription initiation at the promoter (3, 36, 83). However, nucleosome remodeling at promoters does not always appear to be simply a consequence of transcriptional activity but is also thought to mechanistically regulate transcription through modulating the access of trans-acting factors (74).Our understanding of the role that chromatin structure plays in the regulation of RNA Pol I transcription has relatively lagged behind that of Pol II (reviewed in references 6, 21, and

show abstract

Transient Activity Assays of the Trypanosoma brucei Variant Surface Glycoprotein Gene Promoter: Control of Gene Expression at the Posttranscriptional Level

Cited by 8 publications

References 40 publications

Position-dependent and promoter-specific regulation of gene expression in Trypanosoma brucei

Position-dependent and promoter-specific regulation of gene expression in Trypanosoma brucei

The PARP and rRNA Promoters of Trypanosoma brucei Are Composed of Dissimilar Sequence Elements That Are Functionally Interchangeable

Active VSG Expression Sites in Trypanosoma brucei Are Depleted of Nucleosomes

Contact Info

Product

Resources

About