Zhao Yusheng, Xie Shaojun, Li Xiaojie, Wang Chunlei, Chen Zhongzhou, Lai Jinsheng, Gong Zhizhong
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing 100193, China.
Plant Cell. 2014 Jun;26(6):2660-2675. doi: 10.1105/tpc.114.126730. Epub 2014 Jun 10.
In Arabidopsis thaliana, active DNA demethylation is initiated by the DNA glycosylase REPRESSOR OF SILENCING1 (ROS1) and its paralogs DEMETER, DEMETER-LIKE2 (DML2), and DML3. How these demethylation enzymes are regulated, however, is poorly understood. Here, using a transgenic Arabidopsis line harboring the stress-inducible RESPONSIVE TO DEHYDRATION29A (RD29A) promoter-LUCIFERASE (LUC) reporter gene and the cauliflower mosaic virus 35S promoter (35S)-NEOMYCIN PHOSPHOTRANSFERASE II (NPTII) antibiotic resistance marker gene, we characterize a ROS locus, ROS5, that encodes a protein in the small heat shock protein family. ROS5 mutations lead to the silencing of the 35S-NPTII transgene due to DNA hypermethylation but do not affect the expression of the RD29A-LUC transgene. ROS5 physically interacts with the histone acetyltransferase ROS4/INCREASED DNA METHYLATION1 (IDM1) and is required to prevent the DNA hypermethylation of some genes that are also regulated by ROS1 and IDM1. We propose that ROS5 regulates DNA demethylation by interacting with IDM1, thereby creating a chromatin environment that facilitates the binding of ROS1 to erase DNA methylation.
在拟南芥中，活性DNA去甲基化由DNA糖基化酶沉默抑制因子1（ROS1）及其同源物去甲基化酶（DEMETER）、类去甲基化酶2（DML2）和DML3启动。然而，这些去甲基化酶是如何被调控的，目前还知之甚少。在这里，我们使用一个携带胁迫诱导型脱水响应基因29A（RD29A）启动子 - 荧光素酶（LUC）报告基因和花椰菜花叶病毒35S启动子（35S） - 新霉素磷酸转移酶II（NPTII）抗生素抗性标记基因的转基因拟南芥株系，鉴定了一个ROS基因座ROS5，它编码一种小热激蛋白家族的蛋白质。ROS5突变由于DNA超甲基化导致35S - NPTII转基因沉默，但不影响RD29A - LUC转基因的表达。ROS5与组蛋白乙酰转移酶ROS4 / DNA甲基化增加1（IDM1）发生物理相互作用，并且对于防止一些也受ROS1和IDM1调控的基因的DNA超甲基化是必需的。我们提出，ROS5通过与IDM1相互作用来调节DNA去甲基化，从而创造一个有利于ROS1结合以消除DNA甲基化的染色质环境。
