Schmitz Robert J, Sung Sibum, Amasino Richard M
Laboratory of Genetics and Department of Biochemistry, University of Wisconsin, Madison, WI 53706, USA.
Proc Natl Acad Sci U S A. 2008 Jan 15;105(2):411-6. doi: 10.1073/pnas.0710423104. Epub 2008 Jan 4.
Certain plant varieties typically require prolonged exposure to the cold of winter to become competent to flower rapidly in the spring. This process is known as vernalization. In Arabidopsis thaliana, vernalization renders plants competent to flower by epigenetically silencing the strong floral repressor FLOWERING LOCUS C (FLC). As a result of vernalization, levels of lysine-9 and lysine-27 trimethylation on histone 3, modifications that are characteristic of facultative heterochromatin in plants, increase at FLC chromatin. We have identified a mutant, protein arginine methyltransferase 5 (atprmt5), that fails to flower rapidly after vernalization treatment. AtPRMT5 encodes a type II protein arginine methyltransferase (PRMT) that, in winter-annual strains, is required for epigenetic silencing of FLC and for the vernalization-mediated histone modifications characteristic of the vernalized state. Furthermore, the levels of arginine methylation of FLC chromatin increase after vernalization. Therefore, arginine methylation of FLC chromatin is part of the histone code that is required for mitotic stability of the vernalized state.
某些植物品种通常需要长时间暴露在冬季的寒冷环境中，才能在春季迅速具备开花能力。这个过程被称为春化作用。在拟南芥中，春化作用通过对强大的开花抑制因子开花位点C（FLC）进行表观遗传沉默，使植物具备开花能力。春化作用的结果是，组蛋白3上赖氨酸-9和赖氨酸-27三甲基化水平增加，这些修饰是植物兼性异染色质的特征，在FLC染色质上出现。我们鉴定出了一个突变体，即蛋白质精氨酸甲基转移酶5（AtPRMT5），它在春化处理后不能迅速开花。AtPRMT5编码一种II型蛋白质精氨酸甲基转移酶（PRMT），在冬性一年生品系中，它是FLC表观遗传沉默以及春化介导的春化状态特征性组蛋白修饰所必需的。此外，春化作用后FLC染色质的精氨酸甲基化水平增加。因此，FLC染色质的精氨酸甲基化是春化状态有丝分裂稳定性所需组蛋白密码的一部分。
