VSG seq T. brucei
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ABSTRACT:
PROVIDER: PRJEB43907 | ENA |
REPOSITORIES: ENA
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Project description:Trypanosoma brucei is a protozoan parasite that causes human African trypanosomiasis. Its major surface antigen VSG is expressed from subtelomeric loci in a strictly monoallelic manner. We previously showed that the telomere protein TbRAP1 binds dsDNA through its 737RKRRR741 patch to silence VSGs globally. How TbRAP1 permits transcription of the single active VSG is unknown. Through NMR structural analysis, we unexpectedly identify an RNA Recognition Motif (RRM) in TbRAP1, which is unprecedented for RAP1 homologs. Assisted by the 737RKRRR741 patch, TbRAP1 RRM recognizes consensus sequences of VSG 3’UTRs in vitro and binds the active VSG RNA in vivo. Mutating conserved RRM residues abolishes the RNA binding activity, significantly decreases the active VSG RNA level, and derepresses silent VSGs. The competition between TbRAP1’s RNA and dsDNA binding activities suggests a novel mechanism of monoallelic expression, in which the active VSG’s abundant RNA antagonizes TbRAP1’s silencing effect, thereby sustaining its full-level transcription.
2023-02-17 | GSE193394 | GEO
Project description:Trypanosoma brucei VSG Switching - CRISPR/Cas9
| PRJEB40415 | ENA
Project description:T. brucei regularly switches its major surface antigen, VSG, to evade the mammalian host immune response. VSGs are expressed from subtelomeric loci in a strictly monoallelic manner. We identify POLIE as an intrinsic component of the T. brucei telomere complex and examined the effect of POLIE depletion on VSG expression regulation by RNAseq.
2022-01-07 | GSE182941 | GEO
Project description:Trypanosoma brucei brucei strain:VSG 221 (TetR T7RNAP) Transcriptome or Gene expression
| PRJNA248128 | ENA
Project description:As an additional strategy for investigating T. brucei transcriptome responsiveness, the mRNA of a highly important protein, the variant surface glycoprotein (VSG) the major surface protein in the bloodstream stage, was suppressed with RNAi. VSG RNAi results in arrest of cell cycle progression in the bloodstream stage. In addition, the mRNA of a highly important protein for endocytosis, the clathrin heavy chain (CLH), was suppressed with RNAi. CLH knockdown leads to a complete block to endocytosis. We hypothesized that if trypanosomes were able to sense alterations in trafficking and respond to these changes, then depletion of these ORFs by RNAi would be expected to elicit a response at the transcriptome level.<br> <br> part 1: 2 biological replicates of SMB cells transfected with the VSG- RNAi vector grown under normal conditions (non-induced), and 2 replicates of the same cells treated with 1 ug/ml tetracycline (induced) for 24hr, as well as dye swaps were used.<br> <br> part 2: 2 biological replicates of SMB cells transfected with the VSG- RNAi vector grown under normal conditions (non-induced), and 2 replicates of the same cells treated with 1 ug/ml tetracycline (induced) for 3 days, as well as dye swaps were used.<br> <br> part 3: 3 biological replicates of SMB cells transfected with the CLH- RNAi vector grown under normal conditions (non-induced), and 3 replicates of the same cells treated with 1 ug/ml tetracycline (induced), as well as dye swaps were used.
2008-06-26 | E-MEXP-1528 | biostudies-arrayexpress
Project description:Trypanosoma brucei, a member of the Excavates supergroup, falls in an evolutionarily ancient branch of eukaryotes. We have mapped nucleosome positions in T. brucei and identified a map that differs from that of other eukaryotes in several important ways. Unlike in other eukaryotes, the RNA polymerase II initiation regions in T. brucei do not exhibit pronounced nucleosome depletion, and show little evidence for defined -1 and +1 nucleosomes. In contrast, a well-positioned nucleosome is present directly on the splice acceptor sites within the polycistronic transcription units. The RNA polyadenylation sites were depleted of nucleosomes, with a single well-positioned nucleosome present immediately downstream of the predicted sites. The regions flanking the silent Variant Surface Glycoprotein (VSG) gene arrays showed extensive arrays of well-positioned nucleosomes, which may act to repress cryptic transcription initiation. The silent VSG genes themselves exhibited a less regular nucleosomal pattern in both bloodstream and procyclic form trypanosomes. The DNA replication origins, when present within arrays of silent VSG genes, displayed a defined nucleosomal organization compared with replication origins in other chromosomal core regions. Our results indicate that some organizational features of chromatin are evolutionarily ancient, and may already have been present in the last eukaryotic common ancestor.
2017-03-13 | GSE90593 | GEO
Project description:The host range of African trypanosomes is influenced by innate protective molecules in the blood of primates. A subfraction of human high-density lipoprotein (HDL) containing apolipoprotein A-I, apolipoprotein L-I, and haptoglobin-related protein is toxic to Trypanosoma brucei brucei but not the human sleeping sickness parasite Trypanosoma brucei rhodesiense. It is thought that T. b. rhodesiense evolved from a T. b. brucei-like ancestor and expresses a defense protein that ablates the antitrypanosomal activity of human HDL. To directly investigate this possibility, we developed an in vitro selection to generate human HDL-resistant T. b. brucei. Here we show that conversion of T. b. brucei from human HDL sensitive to resistant correlates with changes in the expression of the variant surface glycoprotein (VSG) and abolished uptake of the cytotoxic human HDLs. Complete transcriptome analysis of the HDL-susceptible and -resistant trypanosomes confirmed that VSG switching had occurred but failed to reveal the expression of other genes specifically associated with human HDL resistance, including the serum resistance-associated gene (SRA) of T. b. rhodesiense. In addition, we found that while the original active expression site was still utilized, expression of three expression site-associated genes (ESAG) was altered in the HDL-resistant trypanosomes. These findings demonstrate that resistance to human HDLs can be acquired by T. b. brucei. Keywords: Trypanosoma, VSG, antigenic switching, HDL-resistance
2007-07-04 | GSE8369 | GEO
Project description:We examine the function of the TbRAP1 DB domain in gene expression regulation in Trypanosoma brucei that causes human African trypanosomiasis. TbRAP1 is required for normal VSG monoallelic expression, a key aspect of antigenic variation that is used by T. brucei to evade the host immune response.
2020-09-18 | GSE147734 | GEO
Project description:We examine the function of the TbRAP1 Myb domain in gene expression regulation in Trypanosoma brucei that causes human African trypanosomiasis. TbRAP1 is required for normal VSG monoallelic expression, a key aspect of antigenic variation that is used by T. brucei to evade the host immune response.
2020-02-26 | GSE143456 | GEO