Grünebast Janne, Lorenzen Stephan, Clos Joachim
Leishmania Genetics Group, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
Department of Infection Epidemiology, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany.
mBio. 2025 Jan 8;16(1):e0224124. doi: 10.1128/mbio.02241-24. Epub 2024 Nov 25.
is a human-pathogenic, obligate parasite and the etiological agent of the most prevalent, cutaneous form of leishmaniasis, which is an important neglected, tropical disease with ~1.2 million new infections per year. , and the whole order Trypanosomatida, are early eukaryotes with highly diverged gene expression and regulation pathways, setting them apart from their mammalian hosts and from most other eukaryotes. Using precision run-on sequence analysis, we performed a genome-wide mapping and density analysis of RNA polymerases in isolated nuclei of the protozoan parasite . We map transcription initiation sites at divergent strand switch regions and head-tail regions within the chromosomes and correlate them with known sites of chromatin modifications. We confirm continuous, polycistronic RNA synthesis in all RNA polymerase II-dependent gene arrays but find small varying RNA polymerase activities in polycistronic transcription units (PTUs), excluding gene-specific transcription regulation, but not PTU-specific variations. Lastly, we find evidence for transcriptional pausing of all three RNA polymerase classes, hinting at a possible mechanism of transcriptional regulation.IMPORTANCE spp. are pathogens of humans and animals and cause one of the most important neglected tropical diseases. Regulation of gene expression in but also in the related is radically different from all eukaryotic model organisms, dispensing with regulated, gene-specific transcription, and relying instead on highly regulated translation. Our work sheds light on the initiation, elongation, and termination of transcription, maps unidirectional, polycistronic transcription units, provides evidence for transcriptional pausing at or near starting points of RNA synthesis, and quantifies the varying transcription rates of the polycistronic transcription units. Our results will further the understanding of these important pathogens and should provide a valuable resource for researchers in the field of eukaryotic microbiology.
是一种人类致病性专性寄生虫，也是最常见的皮肤利什曼病的病原体，皮肤利什曼病是一种重要的被忽视的热带疾病，每年约有120万新感染病例。与整个锥虫目一样，是早期真核生物，其基因表达和调控途径高度分化，这使它们有别于其哺乳动物宿主和大多数其他真核生物。我们使用精确的连续序列分析，对原生动物寄生虫分离细胞核中的RNA聚合酶进行了全基因组定位和密度分析。我们在染色体的不同链转换区域和头尾区域定位转录起始位点，并将它们与已知的染色质修饰位点相关联。我们证实了在所有依赖RNA聚合酶II的基因阵列中存在连续的多顺反子RNA合成，但在多顺反子转录单元（PTU）中发现了大小不同的RNA聚合酶活性，排除了基因特异性转录调控，但不包括PTU特异性变异。最后，我们发现了所有三种RNA聚合酶类别的转录暂停证据，这暗示了一种可能的转录调控机制。重要性属是人类和动物的病原体，可导致一种最重要的被忽视的热带疾病。不仅在中的基因表达调控，而且在相关的中的基因表达调控，与所有真核模式生物都有根本不同，它摒弃了受调控的、基因特异性转录，而是依赖于高度调控的翻译。我们的工作揭示了转录的起始、延伸和终止，绘制了单向多顺反子转录单元图谱，为RNA合成起始点或其附近的转录暂停提供了证据，并量化了多顺反子转录单元不同的转录速率。我们的结果将进一步加深对这些重要病原体的理解，并应为真核微生物学领域的研究人员提供宝贵的资源。
