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Trypanosoma brucei histones are heavily modified with combinatorial post-translational modifications and mark Pol II transcription start regions with hyperacetylated H2A.

ABSTRACT: Trypanosomes diverged from the main eukaryotic lineage about 600 million years ago, and display some unusual genomic and epigenetic properties that provide valuable insight into the early processes employed by eukaryotic ancestors to regulate chromatin-mediated functions. We sequenced Trypanosoma brucei core histones by high mass accuracy middle-down mass spectrometry to map core histone post-translational modifications (PTMs) and elucidate cis histone combinatorial PTMs (cPTMs). T. brucei histones are heavily modified and display intricate cPTMs patterns, with numerous hypermodified cPTMs that could contribute to the formation of non repressive euchromatic states. The T. brucei H2A C terminal tail is hyperacetylated, containing up to 5 acetylated lysine residues. MNase-ChIP-seq revealed a striking enrichment of hyperacetylated H2A at Pol II transcription start regions, and showed that H2A histones that are hyperacetylated in different combinations localised to different genomic regions, suggesting distinct epigenetic functions. Our genomics and proteomics data provide insight into the complex epigenetic mechanisms used by this parasite to regulate a genome that lacks the transcriptional control mechanisms found in higher eukaryotes. The findings further demonstrate the complexity of epigenetic mechanisms that were probably shared with the last eukaryotic common ancestor.

INSTRUMENT(S): Orbitrap Fusion ETD

ORGANISM(S): Trypanosoma Brucei

SUBMITTER: JP Maree

LAB HEAD: Hugh George Patterton

PROVIDER: PXD024574 | Pride | 2022-08-21

REPOSITORIES: Pride

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Trypanosoma brucei histones are heavily modified with combinatorial post-translational modifications and mark Pol II transcription start regions with hyperacetylated H2A.

Project description:Trypanosomes diverged from the main eukaryotic lineage about 600 million years ago, and display some unusual genomic and epigenetic properties that provide valuable insight into the early processes employed by eukaryotic ancestors to regulate chromatin-mediated functions. We sequenced Trypanosoma brucei core histones by high mass accuracy middle-down mass spectrometry to map core histone post-translational modifications (PTMs) and elucidate cis‑histone combinatorial PTMs (cPTMs). T. brucei histones are heavily modified and display intricate cPTMs patterns, with numerous hypermodified cPTMs that could contribute to the formation of non‑repressive euchromatic states. The T. brucei H2A C‑terminal tail is hyperacetylated, containing up to 5 acetylated lysine residues. MNase-ChIP-seq revealed a striking enrichment of hyperacetylated H2A at Pol II transcription start regions, and showed that H2A histones that are hyperacetylated in different combinations localised to different genomic regions, suggesting distinct epigenetic functions. Our genomics and proteomics data provide insight into the complex epigenetic mechanisms used by this parasite to regulate a genome that lacks the transcriptional control mechanisms found in higher eukaryotes. The findings further demonstrate the complexity of epigenetic mechanisms that were probably shared with the last eukaryotic common ancestor.

2021-01-19 | GSE165034 | GEO

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2023-08-30 | PXD030364 | Pride

Systematic genetic and proteomic screens identify yeast H2BK37 and mammalian H2BK34 methylation as an evolutionary conserved meiotic mark

Project description:Gametes are highly differentiated cells specialized to carry and protect the parental genetic information. Their chromatin organization is highly compacted and the establishment of this nuclear structure involves many chromatin processes. Technical difficulties exclude the analysis of precise histone mutations during mouse spermatogenesis. The model organism Saccharomyces cerevisiae possesses a differentiation pathway named sporulation with striking similarities with mammalian spermatogenesis. This study took advantage of this yeast pathway and performed a systematic mutational screen on the histone H2A and H2B, revealing the residues which are essential for the formation of spores. Many of them are localized on the lateral side of the nucleosome, highlighting the importance of this surface for meiotic divisions and the formation of spores. Second, histones have been purified at different stages of sporulation and their post-translational modifications analyzed by mass spectrometry. Fifteen new sites of acetylation, methylation or phosphorylation have been identified on the core histones in yeast. Methylation of H2BK37 appears to be a new meiotic mark and is important for Rad51 action. Thus, this modification is conserved during mammalian spermatogenesis when it is found enriched during meiosis. Altogether, our results demonstrate that a combination of genetic and proteomic approaches applied to yeast sporulation can reveal new aspects of chromatin signaling pathways during mammalian spermatogenesis.

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Histone divergence in Trypanosoma brucei results in unique alterations in nucleosome structure

Project description:Eukaryotes have an array of diverse mechanisms for organising and using their genomes, but the histones that make up chromatin are highly conserved. Unusually, histones from Kinetoplastids are highly divergent. The structural and functional consequences of this variation are unknown. Here, we have biochemically characterised nucleosome core particles (NCPs) from the Kinetoplastid parasite Trypanosoma brucei. A structure of the T. brucei NCP reveals that global histone architecture is conserved, but specific sequence alterations lead to distinct DNA and protein interaction interfaces. The T. brucei NCP is unstable and has weakened DNA binding overall. However, dramatic changes at the H2A-H2B interface introduce local reinforcement of DNA contacts. The T. brucei acidic patch has altered topology and is refractory to known binders, indicating that the nature of chromatin interactions in T. brucei may be unique. Overall, our results provide a detailed molecular basis for understanding evolutionary divergence in chromatin structure.

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Trypanosoma brucei histones are heavily modified with combinatorial post-translational modifications and mark Pol II transcription start regions with hyperacetylated H2A.

Project description:Trypanosoma brucei histones are heavily modified with combinatorial post-translational modifications and mark Pol II transcription start regions with hyperacetylated H2A.

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