快速的DNA裂变由LINE-1内核酶靠近DNA末端和不匹配处进行
Bryant D Miller1, Benedict A Smail1, Trevor Van Eeuwen2
1Department of Pathology, Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, USA.
The Journal of biological chemistry
|December 1, 2025
概括
长间隔的元素1 (L1) 内核酶活性是由DNA结构驱动的,而不仅仅是序列. 不匹配和DNA末端显著增强L1内核酶裂变,影响逆转移素插入和基因组稳定性.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 基因组学就是基因组学.
背景情况:
- 长间隔元素1 (LINE-1,L1) 是一种通过RNA复制的真核逆转移子.
- L1插入依赖于向逆转录 (TPRT),涉及其ORF2蛋白 (ORF2p) 与内核酶 (EN) 和逆转录酶 (RT) 域.
- 通过切断DNA,EN启动TPRT,使用L1RNA模板创建RT合成的原料.
研究的目的:
- 调查影响L1内核酶裂变特异性的因素.
- 为了确定L1插入部位的偏好是否是由共识序列中的EN分离或随后的RT初始化决定的.
- 了解DNA结构特征如何影响EN活动.
主要方法:
- 在体外测试中使用线性DNA寡核酸和质粒来评估EN裂变.
- 对不匹配的DNA基质和各种DNA末端配置上的EN活性进行分析.
- 基于序列上下文,不匹配以及DNA末端近距离/组成的分离率的量化.
主要成果:
- 在体外,L1 EN表现出乱交的裂变,在非共识地点切割DNA.
- 在不匹配的DNA位点显著增强裂变 (∼40倍),特别有利于A-G不匹配和T•G/U•G摇摆对.
- 在DNA末端附近,EN切割加速 (>2倍),效率取决于末端类型:5'悬架>3'悬架>凸末端.
结论:
- L1 EN裂变主要由DNA结构形状而不是特定的识别序列决定.
- 不匹配和其他DNA结构变化可以促进EN裂变,可能导致非目标插入.
- 许多L1插入事件可能会在非共识分离后的初始化步骤中失败,影响L1.1的整体基因组影响.
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