在I-C型CRISPR-Cas3中利用激活和失活机制,用于基因组编辑应用程序
bioRxiv : the preprint server for biology
|August 14, 2023
概括
研究人员详细介绍了I-C型CRISPR-Cas系统.
科学领域:
- 分子生物学分子生物学
- 遗传学 遗传学 是一个
- 生物化学 生物化学
背景情况:
- I型CRISPR-Cas系统对于 prokaryotes 的适应性免疫是至关重要的.
- 类型I-C亚型以其紧的结构和在人类细胞中调解大型基因组删除的效率而闻名.
- 了解I-C型的精确机制对于推进基于CRISPR的基因组工程技术至关重要.
研究的目的:
- 通过I-C型CRISPR-Cas系统阐明RNA引导DNA结合和分裂的高分辨率结构机制.
- 为了识别和表征新型抗CRISPR蛋白调节I-C型活性.
- 为控制类型I-C介导的基因组编辑和人类细胞中的转录调制提供工具.
主要方法:
- 利用冷电子显微镜 (cryo-EM) 捕捉了I型C级联DNA复合体的四个不同的结构快照.
- 进行结构分析以确定DNA向和裂变所涉及的结合接口和构造变化.
- 通过结构和功能测试,研究了新发现的抗CRISPR蛋白 (Acrs) 的抑制机制.
主要成果:
- 定义了与目标DNA结合的I型C级联复合体的高分辨率结构,揭示了非目标链 (NTS) 在沿着Cas11子单元的槽中的安置.
- 证明Cas3结合会在NTS中诱导柔性膨胀,从而促进高效的.
- 确定AcrIC8和AcrIC9是I-C型功能的强烈抑制剂,AcrIC8通过直接竞争抑制PAM识别,AcrIC9通过全抑制抑制.
结论:
- 提供了前所未有的结构洞察力,了解了I-C型CRISPR-Cas系统的RNA引导DNA结合和分裂机制.
- 发现了AcrIC8和AcrIC9,为I型-C CRISPR基因组工程的精确控制提供了第一个特征性的"关闭开关".
- 这些发现为在基于CRISPR的治疗和研究应用中提高安全性和可控性铺平了道路.
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