Gu Xiaofeng, Jiang Danhua, Wang Yuqi, Bachmair Andreas, He Yuehui
Department of Biological Sciences, National University of Singapore, Singapore.
Plant J. 2009 Feb;57(3):522-33. doi: 10.1111/j.1365-313X.2008.03709.x. Epub 2008 Oct 8.
The Rad6-Bre1 complex monoubiquitinates histone H2B in target gene chromatin, and plays an important role in positively regulating gene expression in yeast. Here, we show that the Arabidopsis relatives of the yeast Rad6, ubiquitin-conjugating enzyme 1 (UBC1) and UBC2, redundantly mediate histone H2B monoubiquitination, and upregulate the expression of FLOWERING LOCUS C (FLC; a central flowering repressor in Arabidopsis) and FLC relatives, and also redundantly repress flowering, the developmental transition from a vegetative to a reproductive phase that is critical in the plant life cycle. Moreover, we have found that Arabidopsis relatives of the yeast Bre1, including HISTONE MONOUBIQUITINATION 1 (HUB1) and HUB2, also upregulate the expression of FLC and FLC relatives, and that HUB1 genetically interacts with UBC1 and UBC2 to repress the floral transition. These findings are consistent with a model in which HUB1 and HUB2 specifically interact with and direct UBC1 and UBC2 to monoubiquitinate H2B in developmental genes, and thus regulate developmental processes in plants.
Rad6-Bre1复合物对靶基因染色质中的组蛋白H2B进行单泛素化修饰，在酵母中对基因表达的正向调控中发挥重要作用。在此，我们发现酵母Rad6在拟南芥中的同源物，泛素结合酶1（UBC1）和UBC2，冗余介导组蛋白H2B单泛素化，并上调开花抑制因子C（FLC；拟南芥中一个关键的开花抑制因子）及其同源物的表达，还冗余抑制开花，即植物从营养生长阶段到生殖生长阶段的发育转变，这在植物生命周期中至关重要。此外，我们发现酵母Bre1在拟南芥中的同源物，包括组蛋白单泛素化1（HUB1）和HUB2，也上调FLC及其同源物的表达，并且HUB1在遗传上与UBC1和UBC2相互作用以抑制开花转变。这些发现与一个模型一致，即HUB1和HUB2特异性地与UBC1和UBC2相互作用，并指导它们对发育基因中的H2B进行单泛素化修饰，从而调控植物的发育过程。
