Structure and operation of the DNA-translocating type I DNA restriction enzymes
Structure and operation of the DNA-translocating type I DNA restriction enzymes
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DOI：
10.1101/gad.179085.111
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发表时间：
2012-01-01
影响因子：
10.5
通讯作者：
Dryden, David T. F.
中科院分区：
文献类型：
--
作者：
Kennaway, Christopher K.;Taylor, James E.;Dryden, David T. F.
I型DNA限制/修饰(RM)酶是在大多数细菌物种中发现的分子机器。他们的早期发现为遗传工程的发展铺平了道路。它们通过水平基因转移控制(限制)外来DNA流入细菌，同时保持宿主DNA的序列特异性甲基化(修饰)。这些酶在未甲基化的DNA上的内切酶反应之前，数千个碱基对的DNA双向移位到酶上。我们介绍了两种I型RM酶EcoKI和EcoR124I的结构，它们是通过电子显微镜(EM)、小角散射(中子和X射线)和详细的分子模拟得到的。DNA结合会引发酶的开放形式向紧凑形式的大幅收缩。通过使用DNA模拟的反限制蛋白揭示了DNA通过复合体的路径。这些结构揭示了I型RM酶和II型RM酶之间的进化联系。
Type I DNA restriction/modification (RM) enzymes are molecular machines found in the majority of bacterial species. Their early discovery paved the way for the development of genetic engineering. They control (restrict) the influx of foreign DNA via horizontal gene transfer into the bacterium while maintaining sequence-specific methylation (modification) of host DNA. The endonuclease reaction of these enzymes on unmethylated DNA is preceded by bidirectional translocation of thousands of base pairs of DNA toward the enzyme. We present the structures of two type I RM enzymes, EcoKI and EcoR124I, derived using electron microscopy (EM), small-angle scattering (neutron and X-ray), and detailed molecular modeling. DNA binding triggers a large contraction of the open form of the enzyme to a compact form. The path followed by DNA through the complexes is revealed by using a DNA mimic anti-restriction protein. The structures reveal an evolutionary link between type I RM enzymes and type II RM enzymes.