Structure and Mechanisms in RNA-Based Adaptive Immunity, theCRISPR-CasSystem


主题:   Structure and Mechanisms in RNA-Based Adaptive Immunity, theCRISPR-CasSystem主讲人:   Ailong Ke地点:   松江校区四号学院楼3083室时间:   2018-12-13 10:00:00组织单位:   化学化工与生物工程学院

主讲人概况:Ailong Ke is a Professor in the Department of Molecular Biology and Genetics of Cornell University. Dr. Ke is a member of the Graduate Field of Biochemistry, Molecular and Cell Biology, the Graduate Field of Biophysics, and the Graduate Field of Chemistry and Chemical Biology.。

报告内容概况:Type I CRISPR-Cas system features a sequential target-searching and degradation process on double-stranded DNA by the RNA-guided Cascade (CRISPR associated complex for antiviral defense) complex and the nuclease-helicase fusion enzyme Cas3, respectively. Here, Dr.Ke present a 3.7-angstrom-resolution cryo-electron microscopy (cryo-EM) structure of the Type I-E Cascade/R-loop/Cas3 complex, poised to initiate DNA degradation. Cas3 distinguishes Cascade conformations and only captures the R-loop-forming Cascade, to avoid cleaving partially complementary targets. Its nuclease domain recruits the nontarget strand (NTS) DNA at a bulged region for the nicking of single-stranded DNA. An additional 4.7-angstrom-resolution cryo-EM structure captures the postnicking state, in which the severed NTS retracts to the helicase entrance, to be threaded for adenosine 5'-triphosphate-dependent processive degradation. These snapshots form the basis for understanding.

视频:   摄影: 撰写:陆昌瑞  信息员:陈娜  编辑:朱一超



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