H3 K4和K79的甲基化并不严格依赖于H2B K123的泛素化。
Methylation of H3 K4 and K79 is not strictly dependent on H2B K123 ubiquitylation.
作者信息
Foster Elinor R, Downs Jessica A
机构信息
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, England, UK.
出版信息
J Cell Biol. 2009 Mar 9;184(5):631-8. doi: 10.1083/jcb.200812088. Epub 2009 Mar 2.
Covalent modifications of histone proteins have profound consequences on chromatin structure and function. Specific modification patterns constitute a code read by effector proteins. Studies from yeast found that H3 trimethylation at K4 and K79 is dependent on ubiquitylation of H2B K123, which is termed a "trans-tail pathway." In this study, we show that a strain unable to be ubiquitylated on H2B (K123R) is still proficient for H3 trimethylation at both K4 and K79, indicating that H3 methylation status is not solely dependent on H2B ubiquitylation. However, additional mutations in H2B result in loss of H3 methylation when combined with htb1-K123R. Consistent with this, we find that the original strain used to identify the trans-tail pathway has a genomic mutation that, when combined with H2B K123R, results in defective H3 methylation. Finally, we show that strains lacking the ubiquitin ligase Bre1 are defective for H3 methylation, suggesting that there is an additional Bre1 substrate that in combination with H2B K123 facilitates H3 methylation.
组蛋白的共价修饰对染色质的结构和功能有着深远影响。特定的修饰模式构成了一种由效应蛋白读取的密码。来自酵母的研究发现,H3在K4和K79位点的三甲基化依赖于H2B K123位点的泛素化,这被称为“跨尾部途径”。在本研究中,我们发现一个在H2B上无法进行泛素化的菌株(K123R)在K4和K79位点的H3三甲基化方面仍然正常,这表明H3甲基化状态并非仅仅依赖于H2B泛素化。然而,当与htb1 - K123R结合时,H2B中的其他突变会导致H3甲基化缺失。与此一致的是,我们发现用于鉴定跨尾部途径的原始菌株存在一个基因组突变,当与H2B K123R结合时,会导致H3甲基化缺陷。最后,我们表明缺乏泛素连接酶Bre1的菌株在H3甲基化方面存在缺陷,这表明存在一种额外的Bre1底物,它与H2B K123共同作用促进H3甲基化。