Ontology highlight
ABSTRACT:
PROVIDER: PRJNA1234166 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR32636017_1.fastq.gz | Fastqsanger.gz | |||
| SRR32636017_2.fastq.gz | Fastqsanger.gz | |||
| SRR32636018_1.fastq.gz | Fastqsanger.gz | |||
| SRR32636018_2.fastq.gz | Fastqsanger.gz | |||
| SRR32636019_1.fastq.gz | Fastqsanger.gz |
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Project description:Transcription of protein coding genes in trypanosomatids is atypical and almost exclusively polycistronic. In Trypanosoma brucei, approximately 150 polycistrons, and 8000 genes, are constitutively transcribed by RNA polymerase II, while a smaller subset can be transcribed by RNA polymerase I. RNA polymerase II promoters are unconventional and characterised by regions of chromatin enriched for histones with specific patterns of post-translational modification on their highly divergent N-terminal tails. To investigate the roles of histone tail-residues in gene expression control in T. brucei, we engineered strains exclusively expressing novel mutant histones. We used an inducible CRISPR-Cas9 system to delete >40 native copies of histone H4, complementing the tandem arrays with a single ectopic H4 gene. The resulting ‘histoneH4’ strains were validated using whole-genome sequencing and transcriptome analysis. We then performed saturation mutagenesis of six histone H4 N-terminal tail lysine (K) residues and used multiplex amplicon-seq to profile the relative fitness of 384 distinct precision edited mutants. H4K10 mutations were not tolerated, but we could derive a panel of nineteen strains exclusively expressing novel H4K4 or H4K14 mutants. Both proteomic and transcriptomic analysis of H4K4Q mutants revealed significantly reduced expression of genes adjacent to RNA polymerase II promoters, where the glutamine (Q) mutation mimics an abnormally high level of acetylation. Thus, we present direct evidence for polycistronic expression control by histone H4 N-terminal tails in trypanosomes.
2025-03-11 | PXD061709 | Pride
Project description:Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas’ disease, a chronic and potentially fatal disease that causes irreversible damage to heart and digestive tract in humans. Like all trypanosomes, the protein coding genes of T. cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Therefore, trypanosomes presumably rely on post-transcriptional process to regulate gene expression. Pol II promoters have not been identified and there is no evidence for regulated gene expression at the transcriptional level. However, the presence of the hyper-modified DNA base J, Beta-D-glucosyl hydroxymethyluracil, at regions flanking the polycistronic units (PTU) in T. brucei suggested its involvement in regulating Pol II transcription. We now demonstrate that base J is localized at PTU flanking regions in T. cruzi and levels are differentially regulated by the thymidine hydroxylases, JBP1 and JBP2, involved in J biosynthesis. Microarray analysis of the JBP1dKO and JBP2dKO indicate the up and down regulation of several hundred genes distributed throughout the genome. We show a large increase in Pol II transcription rate following the decrease in base J at the PTU flanks. Changes in gene expression include virulence genes and parasites are defective in host cell invasion and egress. There is a direct correlation between the reduction in base J levels, number of genes affected and strength of the virulence phenotype. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids and provides a biological role of the only hyper-modified DNA base in eukaryotes.
2011-01-01 | GSE23855 | GEO
Project description:Protein coding genes in the trypanosome genome are organized in polycistronic transcription units (PTUs). How RNA Polymerase II (Pol II) initiates PTU transcription has not been resolved and the current model favors initiation driven by chromatin epigenetic marks, rather than core-promoters. Here, we identify sequence-specific core promoters by functional characterization of ChIP-Seq Pol II accumulation-peaks. Sequences located between oppositely orientated PTUs contained two independent and distinct core promoters, driving unidirectional transcription. Detailed analysis of one promoter identified 75 bp, necessary and sufficient to fully drive reporter expression, and containing short functional motifs. Analysis of further promoters suggested activity and initiation is regulated and both, focused and dispersed transcription patterns were found. Thus, in contrast to the model of unregulated and promoter-independent transcription initiation, sequence-specific promoters determine the initiation of RNA Pol II transcription of protein coding genes in trypanosomes. These findings resolve the discrepancy between trypanosomes and other eukaryotes in how Pol II initiates protein-coding gene transcription.
2021-02-01 | GSE130798 | GEO
Project description:Trypanosoma cruzi, a flagellated protozoan, is the causative agent of Chagas’ disease, a chronic and potentially fatal disease that causes irreversible damage to heart and digestive tract in humans. Like all trypanosomes, the protein coding genes of T. cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Therefore, trypanosomes presumably rely on post-transcriptional process to regulate gene expression. Pol II promoters have not been identified and there is no evidence for regulated gene expression at the transcriptional level. However, the presence of the hyper-modified DNA base J, Beta-D-glucosyl hydroxymethyluracil, at regions flanking the polycistronic units (PTU) in T. brucei suggested its involvement in regulating Pol II transcription. We now demonstrate that base J is localized at PTU flanking regions in T. cruzi and levels are differentially regulated by the thymidine hydroxylases, JBP1 and JBP2, involved in J biosynthesis. Microarray analysis of the JBP1dKO and JBP2dKO indicate the up and down regulation of several hundred genes distributed throughout the genome. We show a large increase in Pol II transcription rate following the decrease in base J at the PTU flanks. Changes in gene expression include virulence genes and parasites are defective in host cell invasion and egress. There is a direct correlation between the reduction in base J levels, number of genes affected and strength of the virulence phenotype. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids and provides a biological role of the only hyper-modified DNA base in eukaryotes. J1 and J2 null mutant trypomastigotes were each compared to wild type trypomastigotes. There were 3 biological replicates for each comparison.
2011-01-01 | E-GEOD-23855 | biostudies-arrayexpress
Project description:Unlike other eukaryotes, the protein coding genes of Trypanosoma cruzi are arranged into large polycistronic gene clusters transcribed by polymerase II (Pol II). Thus, trypanosomes rely on post-transcriptional processes to regulate gene expression. Here, we show that the glucosylated thymine DNA base (-D-glucosyl hydroxymethyluracil or base J) is present within sequences flanking the polycistronic units (PTU) in T. cruzi. loss of base J at sites of transcription initiation, via deletion of the two enzymes that regulate J synthesis (JBP1 and JBP2), correlates with an increased rate of Pol II transcription and subsequent genome-wide increase in gene expression. genes include virulence genes and the resulting parasites are defective in host cell invasion and egress. These studies indicate that base J represents an epigenetic factor regulating Pol II transcription initiation in kinetoplastids, and provides the first biological role of the only hyper-modified DNA base in eukaryotes. This entry contains the results using SLT, digital gene expression profiling of tags read off the spliced leader sequence of all mature trypanosomatid messages, for the life-cycle of T. cruzi, four stages, in wild-type as well as JBP1 KO cells.
2011-01-21 | GSE26754 | GEO
Project description:Under continuous, glucose-limited conditions, budding yeast exhibit robust metabolic cycles associated with major oscillations of gene expression and metabolic state. However, how such fluctuations might be coordinately linked to changes in chromatin status is less well understood. Here, we examine the correlated genome-wide transcription and chromatin states across the yeast metabolic cycle (YMC) at unprecedented temporal resolution, revealing a "just in time supply chain" by which specific cellular processes such as ribosome biogenesis are coordinated in time with remarkable precision. We identify distinct chromatin and splicing patterns associated with different gene categories and determine the relative timing of chromatin modifications to maximal transcription. Additionally, we interrogate chromatin modifier occupancy and observe subtly distinct spatial and temporal patterns compared to the modifications themselves. Furthermore, we identify multiple lysine mutants in H3 or H4 tails that disrupt metabolic cycling, supporting a potentially cooperative role of histone modifications in the YMC. 16 time points RNA-seq and ChIP-seq of 8 histone marks over one metabolic cycle, 14 time points ChIP-seq of 3 chromatin modifiers over one metabolic cycle
2014-08-31 | E-GEOD-52339 | biostudies-arrayexpress
Project description:Lysine methylation on histone tails impacts genome regulation and cell fate determination in many developmental processes. Apicomplexa intracellular parasites cause major diseases and they have developed complex life cycles with fine-tuned differentiation events. Yet, apicomplexa genomes have few transcription factors and little is known about their epigenetic control systems. Tick-borne Theileria apicomplexa species have relatively small, compact genomes and a remarkable ability to transform leukocytes in their bovine hosts. Here we report enriched H3 lysine 18 monomethylation (H3K18me1) on the gene bodies of repressed genes in Theileria macroschizonts. Differentiation to merozoites (merogony) led to decreased H3K18me1 in parasite nuclei. Pharmacological manipulation of H3K18 acetylation or methylation impacted parasite differentiation and expression of stage-specific genes. Finally, we identified a parasite SET-domain methyltransferase (TaSETup1) that can methylate H3K18 and represses gene expression. Thus, H3K18me1 emerges as an important epigenetic mark which controls gene expression and stage differentiation in Theileria parasites.
2021-03-25 | PXD024599 | Pride
Project description:mRNA export is central to gene regulation and expression. In trypanosomes, transcription is polycistronic, all mRNAs are processed by trans-splicing and export is mediated by non-canonical mechanisms. We have described several conserved mRNA export pathway components in Trypanosoma cruzi, including orthologs of Sub2, a component of the TREX complex, and eIF4AIII, a core component of the exon junction complex (EJC). Few orthologs of proteins involved in mRNA export in higher eukaryotes are detectable in trypanosome genomes and examples of mechanistic divergence well known. To uncover additional components of the trypanosome mRNA maturation and export system we undertook an unbiased search for protein interactors of TcSub2 and TceIF4AIII. Significant overlap between TcSub2 and TceIF4AIII interacting protein cohorts suggests that both proteins associate with similar machinery. We confirmed several interactions with conserved core components of the EJC and multiple additional complexes, together with identification of proteins specific to trypanosomatids. The highly interactive super-interactome uncovered here, capable of supporting RNA processing from splicing through to nuclear export and cytoplasmic events, highlights kinetoplastid-specific and conserved components creating an amalgam to support the unique mRNA maturation mechanisms in trypanosomes.
2022-02-07 | PXD028072 | Pride
Project description:Using histone H3 mutants designed so that they can only form a heterodimer, we studied the gene expression in a collection of mutants, comparing mutations to one histone H3 tail of a nucleosome compared to two histone H3 tails of a nucleosome.
2020-05-01 | GSE81531 | GEO
Project description:Identification of sequence-specific promoters driving polycistronic transcription initiation by RNA Polymerase II in trypanosomes
| PRJNA541456 | ENA