DNA RESTRICTION-MODIFICATION ENZYMES OF PHAGE-P1 AND PLASMID-P15B - SUBUNIT FUNCTIONS AND STRUCTURAL HOMOLOGIES
DNA RESTRICTION-MODIFICATION ENZYMES OF PHAGE-P1 AND PLASMID-P15B - SUBUNIT FUNCTIONS AND STRUCTURAL HOMOLOGIES
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DOI：
10.1016/s0022-2836(83)80240-x
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发表时间：
1983-01-01
影响因子：
5.6
通讯作者：
BICKLE, TA
中科院分区：
文献类型：
--
作者：
HADI, SM;BACHI, B;BICKLE, TA
III型限制性内切酶EcoP 1和EcoP 15从细菌[大肠杆菌]中纯化至同质，所述细菌含有克隆在小的多拷贝质粒上的酶的结构基因，并且过量产生酶。这两种酶都含有2种不同的亚基。两种酶的亚基的MW相同，针对一种酶制备的抗体与另一种酶的两个亚基交叉反应。含有质粒衍生物的细菌，其中一个结构基因的大部分已被删除，具有限制性，修饰+，表型，仅含有2个亚基中较小的一个。该亚基必须是识别特定DNA序列并在修饰反应中使其甲基化的亚基（限制性内切酶本身也充当修饰甲基化酶）。从这些缺失衍生物中纯化P1和P15修饰亚基，它们具有预期的性质;它们是序列特异性修饰甲基化酶。携带完整限制/修饰系统的菌株还含有可能负责体内修饰的游离修饰亚基库。
The type III restriction enzymes EcoP1 and EcoP15 were purified to homogeneity from bacteria [Escherichia coli] that contain the structural genes for the enzymes cloned on small, muticopy plasmids and which overproduce the enzymes. Both of the enzymes contain 2 different subunits. The MW of the subunits are the same for both enzymes and antibodies prepared against 1 enzyme cross-react with both subunits of the other. Bacteria containing a plasmid derivative in which a large part of one of the structural genes has been deleted have a restriction-, modification+, phenotype and contain only the smaller of the 2 subunits. This subunit must be the one that recognizes the specific DNA sequence and methylates it in the modification reaction (the restriction enzyme itself also acts as a modification methylase). The P1 and P15 modification subunits were purified from these deletion derivatives and they have the expected properties; they are sequence-specific modification methylases. Strains carrying the full restriction/modification system also contain a pool of free modification subunits that might be responsible for in vivo modification.