Department of Veterinary Sciences, Experimental Parasitology, Ludwig-Maximilians-Universität München, 80752, Munich, Germany.
Biomedical Center Munich, Department of Physiological Chemistry, Ludwig-Maximilians-Universität München, 82152, Planegg-Martinsried, Germany.
Nat Commun. 2020 Mar 20;11(1):1498. doi: 10.1038/s41467-020-15274-0.
Despite histone H2A variants and acetylation of histones occurring in almost every eukaryotic organism, it has been difficult to establish direct functional links between canonical histones or H2A variant acetylation, deposition of H2A variants and transcription. To disentangle these complex interdependent processes, we devised a highly sensitive strategy for quantifying histone acetylation levels at specific genomic loci. Taking advantage of the unusual genome organization in Trypanosoma brucei, we identified 58 histone modifications enriched at transcription start sites (TSSs). Furthermore, we found TSS-associated H4 and H2A.Z acetylation to be mediated by two different histone acetyltransferases, HAT2 and HAT1, respectively. Whereas depletion of HAT2 decreases H2A.Z deposition and shifts the site of transcription initiation, depletion of HAT1 does not affect H2A.Z deposition but reduces total mRNA levels by 50%. Thus, specifically reducing H4 or H2A.Z acetylation levels enabled us to reveal distinct roles for these modifications in H2A.Z deposition and RNA transcription.
尽管组蛋白 H2A 变体和组蛋白乙酰化在几乎所有真核生物中都存在，但很难建立规范组蛋白或 H2A 变体乙酰化、H2A 变体沉积与转录之间的直接功能联系。为了理清这些复杂的相互依存的过程，我们设计了一种高度敏感的策略，用于定量特定基因组位置的组蛋白乙酰化水平。利用布氏锥虫异常的基因组组织，我们鉴定了 58 种在转录起始位点（TSS）富集的组蛋白修饰。此外，我们发现与 TSS 相关的 H4 和 H2A.Z 乙酰化分别由两种不同的组蛋白乙酰转移酶 HAT2 和 HAT1 介导。HAT2 的消耗降低了 H2A.Z 的沉积并改变了转录起始的位置，而 HAT1 的消耗不影响 H2A.Z 的沉积，但使总 mRNA 水平降低了 50%。因此，特异性降低 H4 或 H2A.Z 乙酰化水平使我们能够揭示这些修饰在 H2A.Z 沉积和 RNA 转录中的不同作用。
