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EMBO J. 2017 Sep 1;36(17):2581-2594. doi: 10.15252/embj.201695323. Epub 2017 Jul 12.

GT-rich promoters can drive RNA pol II transcription and deposition of H2A.Z in African trypanosomes.

Author information

1
Research Center for Infectious Diseases, Universität Würzburg, Würzburg, Germany.
2
Core Unit Systems Medicine, Universität Würzburg, Würzburg, Germany.
3
Research Center for Infectious Diseases, Universität Würzburg, Würzburg, Germany n.siegel@lmu.de.
4
Department of Veterinary Sciences, Experimental Parasitology, Ludwig-Maximilians-Universität München, München, Germany.
5
Biomedical Center Munich, Physiological Chemistry, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany.

Abstract

Genome-wide transcription studies are revealing an increasing number of "dispersed promoters" that, unlike "focused promoters", lack well-conserved sequence motifs and tight regulation. Dispersed promoters are nevertheless marked by well-defined chromatin structures, suggesting that specific sequence elements must exist in these unregulated promoters. Here, we have analyzed regions of transcription initiation in the eukaryotic parasite Trypanosoma brucei, in which RNA polymerase II transcription initiation occurs over broad regions without distinct promoter motifs and lacks regulation. Using a combination of site-specific and genome-wide assays, we identified GT-rich promoters that can drive transcription and promote the targeted deposition of the histone variant H2A.Z in a genomic context-dependent manner. In addition, upon mapping nucleosome occupancy at high resolution, we find nucleosome positioning to correlate with RNA pol II enrichment and gene expression, pointing to a role in RNA maturation. Nucleosome positioning may thus represent a previously unrecognized layer of gene regulation in trypanosomes. Our findings show that even highly dispersed, unregulated promoters contain specific DNA elements that are able to induce transcription and changes in chromatin structure.

KEYWORDS:

Trypanosoma brucei ; core promoter; histone variant; nucleosome occupancy

PMID:
28701485
PMCID:
PMC5579346
DOI:
10.15252/embj.201695323
[Indexed for MEDLINE]
Free PMC Article

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