TYPE-III RESTRICTION ENZYMES NEED 2 INVERSELY ORIENTED RECOGNITION SITES FOR DNA CLEAVAGE
TYPE-III RESTRICTION ENZYMES NEED 2 INVERSELY ORIENTED RECOGNITION SITES FOR DNA CLEAVAGE
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DOI：
10.1038/355467a0
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发表时间：
1992-01-30
期刊：
影响因子：
64.8
通讯作者：
SCHROEDER, C
中科院分区：
文献类型：
--
作者：
MEISEL, A;BICKLE, TA;SCHROEDER, C
III型限制/修饰酶识别短的、非回文序列，这些序列只能在一条链上被甲基化，矛盾的结果是，在实际半甲基化DNA的复制过程中，出现了完全未修饰的位点1。为什么未经修改的网站不受自杀限制尚不清楚。在这里，我们表明，限制需要两个未修改的识别位点，可以由不同的距离分开，但必须在相反的方向。在新复制的DNA中，所有未修饰的位点当然都在同一方向上，这就解释了为什么它们不受限制。这一结果可能与双链DNA的其他各向异性表现有关，如遗传印记2。
TYPE III restriction/modification enzymes recognize short, non-palindromic sequences that can be methylated on only one strand, with the paradoxical consequence that during replication of what is in effect hemimethylated DNA totally unmodified sites arise 1. Why the unmodified sites are not subject to suicidal restriction was not clear. Here we show that restriction requires two unmodified recognition sites that can be separated by different distances but which must be in inverse orientation. All of the unmodified sites in newly replicated DNA are of course in the same orientation, which explains why they are not restricted. This result may be of relevance to other manifestations of anisotropy in double-stranded DNA, such as genetic imprinting 2.