Zakharova M V, Kravetz A N, Beletzkaja I V, Repyk A V, Solonin A S
Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region.
Gene. 1993 Jul 15;129(1):77-81. doi: 10.1016/0378-1119(93)90698-3.
The genes encoding the CfrBI restriction and modification (R-M) systems from Citrobacter freundii and recognizing the sequence 5'-CCWWGG-3' (W = A or T) were cloned in Escherichia coli McrBC- cells. The nucleotide (nt) sequences of the genes were determined. Two large open reading frames were found. Deletion analysis showed that one of them [1128 nt coding for 376 amino acids (aa)] corresponds to a methyltransferase (MTase)-encoding gene and the other (1065 nt coding for 355 aa) to a restriction endonuclease-encoding gene. The genes are oriented divergently and separated by 76 bp. A CfrBI site (5'-m4CCATGG) was found in the intergenic region of the cfrBIRM genes. Analysis of the deduced aa sequence of M.CfrBI made it possible to determine the typical features of a m4C-specific MTase. Limited homology between the M.CfrBI and R.CfrBI proteins was also found.
编码来自弗氏柠檬酸杆菌的CfrBI限制与修饰（R-M）系统且识别序列5'-CCWWGG-3'（W = A或T）的基因被克隆到大肠杆菌McrBC-细胞中。测定了这些基因的核苷酸（nt）序列。发现了两个大的开放阅读框。缺失分析表明，其中一个[1128 nt编码376个氨基酸（aa）]对应于一个甲基转移酶（MTase）编码基因，另一个（1065 nt编码355个aa）对应于一个限制性内切核酸酶编码基因。这些基因呈反向排列，间隔76 bp。在cfrBIRM基因的基因间区域发现了一个CfrBI位点（5'-m4CCATGG）。对推导的M.CfrBI氨基酸序列的分析使得确定m4C特异性MTase的典型特征成为可能。还发现了M.CfrBI和R.CfrBI蛋白之间的有限同源性。
