Schmitz Robert Jeffrey, Tamada Yosuke, Doyle Mark Robert, Zhang Xiaoyu, Amasino Richard Mark
Department of Biochemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
Plant Physiol. 2009 Feb;149(2):1196-204. doi: 10.1104/pp.108.131508. Epub 2008 Dec 17.
The spectrum of histone modifications at a given locus is a critical determinant for the correct output of gene expression. In Arabidopsis (Arabidopsis thaliana), many studies have examined the relationship between histone methylation and gene expression, but few studies exist on the relationship between other covalent histone modifications and gene expression. In this work, we describe the role of histone H2B deubiquitination in the activation of gene expression and the consequence of a perturbation of histone H2B deubiquitination in the timing of the floral transition in Arabidopsis. A mutation in a H2B deubiquitinase, UBIQUITIN-SPECIFIC PROTEASE26 (UBP26), results in an early-flowering phenotype. In the ubp26 mutant, mRNA levels of the floral repressor FLOWERING LOCUS C (FLC) and other related family members is decreased. Furthermore, this mutant accumulates H2B monoubiquitination, and has decreased levels of H3K36 trimethylation and increased levels of H3K27 trimethylation at the FLC locus. Thus, UBP26 is required for transcriptional activation of FLC through H2B deubiquitination and is consistent with a model in which deubiquitination is necessary for the accumulation of H3K36 trimethylation and the proper level of transcriptional activation.
给定基因座处的组蛋白修饰谱是基因表达正确输出的关键决定因素。在拟南芥中，许多研究探讨了组蛋白甲基化与基因表达之间的关系，但关于其他共价组蛋白修饰与基因表达之间关系的研究较少。在这项工作中，我们描述了组蛋白H2B去泛素化在基因表达激活中的作用，以及拟南芥中组蛋白H2B去泛素化扰动对开花转变时间的影响。H2B去泛素化酶泛素特异性蛋白酶26（UBP26）中的一个突变导致早花表型。在ubp26突变体中，开花抑制因子开花位点C（FLC）和其他相关家族成员的mRNA水平降低。此外，该突变体积累H2B单泛素化，并且在FLC基因座处H3K36三甲基化水平降低，H3K27三甲基化水平升高。因此，UBP26通过H2B去泛素化对FLC的转录激活是必需的，这与一种模型一致，即去泛素化对于H3K36三甲基化的积累和适当水平的转录激活是必要的。
