基质特异性和蛋白质稳定性推动了植物特异性DNA甲基转移酶的分歧
Jianjun Jiang1,2, Jia Gwee1,3, Jian Fang4
1Wisconsin Institute for Discovery and Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53715, USA.
Science advances
|November 6, 2024
概括
植物DNA甲基化酶CMT2和CMT3演化出了不同的作用. 来自CMT3重复的CMT2由于氨基酸变化而失去了CHG甲基化能力,影响了基因组完整性.
科学领域:
- 表观遗传学和基因组学
- 植物分子生物学 植物分子生物学
- 进化生物学 进化生物学
背景情况:
- 基因组甲基化是基因组稳定性和转子子沉默的关键表观遗传机制.
- 在植物中,染色甲基酶3 (CMT3) 和染色甲基酶2 (CMT2) 在不同的序列环境中甲基化DNA (分别是CHG和CHH).
- 在CMT3和CMT2之间基质特异性的进化差异尚未得到充分理解.
研究的目的:
- 研究植物DNA甲基转移酶CMT2和CMT3.3的进化起源和功能分歧.
- 阐明CMT2基质特异性的分子基础及其在DNA甲基化模式中的作用.
- 了解植物中DNA甲基化的进化轨迹.
主要方法:
- 遗传学分析以追踪CMT2的进化起源.
- 位点定向突变发生,以调查特定氨基酸残留在CMT2功能中的作用.
- 使用遗传和生物化学方法分析Arabidopsis突变物中的DNA甲基化模式.
主要成果:
- CMT2的进化源于在开花植物中复制古老的CMT3基因.
- 在CMT3中一个关键的氨酸残留物,对于CHG甲基化至关重要,在CMT2中缺席,损害了其CHG活性.
- 在CMT2中恢复该残留物重新建立了CHG和CHH甲基化,表明CHG甲基化在进化过程中的功能丧失;CMT2的N端在热应力下提供稳定性.
结论:
- 通过进化变化,CMT2和CMT3在基质特异性上有所不同,主要是CMT2中CHG甲基化活性的丧失.
- 这种分歧影响了植物中特定的DNA甲基化模式的维持.
- 该研究提供了关于表观遗传机制的演变及其在基因组功能中的作用的见解.
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