Department of Biochemistry and Molecular Genetics, University of Colorado, Denver - School of Medicine, 12801 E. 17th Ave., Aurora, CO, 80045, USA.
Curr Genet. 2018 Aug;64(4):799-806. doi: 10.1007/s00294-018-0812-1. Epub 2018 Feb 20.
Mono-ubiquitinated histone H2B (H2B-Ub) is important for chromatin regulation of transcription, chromatin assembly, and also influences heterochromatin. In this review, we discuss the effects of H2B-Ub from nucleosome to higher-order chromatin structure. We then assess what is currently known of the role of H2B-Ub in heterochromatic silencing in budding and fission yeasts (S. cerevisiae and S. pombe), which have distinct silencing mechanisms. In budding yeast, the SIR complex initiates heterochromatin assembly with the aid of a H2B-Ub deubiquitinase, Ubp10. In fission yeast, the RNAi-dependent pathway initiates heterochromatin in the context of low H2B-Ub. We examine how the different silencing machineries overcome the challenge of H2B-Ub chromatin and highlight the importance of using these microorganisms to further our understanding of H2B-Ub in heterochromatic silencing pathways.
单泛素化组蛋白 H2B（H2B-Ub）对于转录的染色质调控、染色质组装很重要，也会影响异染色质。在这篇综述中，我们讨论了从核小体到更高阶染色质结构的 H2B-Ub 的影响。然后，我们评估了目前已知的 H2B-Ub 在芽殖酵母（酿酒酵母）和裂殖酵母（裂殖酵母）中异染色质沉默中的作用，这两种酵母具有不同的沉默机制。在芽殖酵母中，SIR 复合物在 H2B-Ub 去泛素酶 Ubp10 的帮助下启动异染色质组装。在裂殖酵母中，RNAi 依赖性途径在低 H2B-Ub 的情况下启动异染色质。我们研究了不同的沉默机制如何克服 H2B-Ub 染色质的挑战，并强调了利用这些微生物来进一步了解 H2B-Ub 在异染色质沉默途径中的重要性。
