Bewick Adam J, Ji Lexiang, Niederhuth Chad E, Willing Eva-Maria, Hofmeister Brigitte T, Shi Xiuling, Wang Li, Lu Zefu, Rohr Nicholas A, Hartwig Benjamin, Kiefer Christiane, Deal Roger B, Schmutz Jeremy, Grimwood Jane, Stroud Hume, Jacobsen Steven E, Schneeberger Korbinian, Zhang Xiaoyu, Schmitz Robert J
Department of Genetics, University of Georgia, Athens, GA 30602;
Institute of Bioinformatics, University of Georgia, Athens, GA 30602;
Proc Natl Acad Sci U S A. 2016 Aug 9;113(32):9111-6. doi: 10.1073/pnas.1604666113. Epub 2016 Jul 25.
In plants, CG DNA methylation is prevalent in the transcribed regions of many constitutively expressed genes (gene body methylation; gbM), but the origin and function of gbM remain unknown. Here we report the discovery that Eutrema salsugineum has lost gbM from its genome, to our knowledge the first instance for an angiosperm. Of all known DNA methyltransferases, only CHROMOMETHYLASE 3 (CMT3) is missing from E. salsugineum Identification of an additional angiosperm, Conringia planisiliqua, which independently lost CMT3 and gbM, supports that CMT3 is required for the establishment of gbM. Detailed analyses of gene expression, the histone variant H2A.Z, and various histone modifications in E. salsugineum and in Arabidopsis thaliana epigenetic recombinant inbred lines found no evidence in support of any role for gbM in regulating transcription or affecting the composition and modification of chromatin over evolutionary timescales.
在植物中，CG DNA甲基化在许多组成型表达基因的转录区域（基因体甲基化；gbM）中普遍存在，但gbM的起源和功能仍不清楚。在此，我们报告一项发现，即盐芥（Eutrema salsugineum）基因组中已丢失gbM，据我们所知，这是被子植物中的首例。在所有已知的DNA甲基转移酶中，盐芥中仅缺少染色体甲基转移酶3（CMT3）。另一种独立丢失CMT3和gbM的被子植物——扁果亚麻芥（Conringia planisiliqua）的鉴定结果支持了CMT3是建立gbM所必需的这一观点。对盐芥和拟南芥表观遗传重组自交系中的基因表达、组蛋白变体H2A.Z以及各种组蛋白修饰进行的详细分析，没有发现任何证据支持gbM在进化时间尺度上对转录调控或影响染色质组成和修饰起任何作用。
