Characterization of the methyl-specific restriction system of Streptomyces coelicolor A3(2) and of the role played by laterally acquired nucleases
Characterization of the methyl-specific restriction system of Streptomyces coelicolor A3(2) and of the role played by laterally acquired nucleases
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DOI：
10.1111/j.1574-6968.2009.01790.x
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发表时间：
2009-12-01
影响因子：
2.1
通讯作者：
Servin-Gonzalez, Luis
中科院分区：
文献类型：
--
作者：
Gonzalez-Ceron, Gabriela;Josue Miranda-Olivares, Osvaldo;Servin-Gonzalez, Luis
通过用未甲基化和甲基化的pSET 152 DNA进行转化，分析天蓝色链霉菌A3（2）的甲基特异性限制性酶切系统。天蓝色链霉菌对大肠杆菌Dam、Dcm和Hsd修饰系统的DNA甲基化有很强的抑制作用。尽管质粒上的位点明显较少，但Hsd修饰的DNA与Dam修饰的DNA一样受到强烈的限制; Dcm修饰的质粒比Dam或Hsd修饰的DNA受到更强烈的限制。在体外由不同的甲基化酶修饰的质粒DNA的限制也表现出更大的依赖于甲基化序列比甲基化位点的数量。构建天蓝色链霉菌突变体，其缺乏被鉴定为编码甲基特异性限制性核酸酶（SCO 4213、SCO 4631和SCO 2863基因的产物，以及SCO 3261-SCO 3262操纵子）的可能候选者的基因，所述甲基特异性限制性核酸酶位于天蓝色链霉菌的横向获得的基因组岛中。coelicolor染色体;这些突变体表现出部分缓解甲基化DNA限制。这些基因在近缘变铅青链霉菌中的克隆增加了该物种对甲基化DNA的限制，证实了它们作为链霉菌甲基特异性限制系统的一部分的作用。天蓝色。
The methyl-specific restriction system of Streptomyces coelicolor A3(2) was analyzed by carrying out transformations with unmethylated and methylated pSET152 DNA. Streptomyces coelicolor was found to strongly restrict DNA methylated in vivo by the Dam, Dcm and Hsd modification systems of Escherichia coli. Hsd-modified DNA was restricted as strongly as Dam-modified DNA, even though there are significantly fewer sites on the plasmid; Dcm-modified plasmid was restricted more strongly then either Dam-or Hsd-modified DNA. Restriction of plasmid DNA modified in vitro by different methylases also showed a greater dependence on the methylated sequence than on the number of methylated sites. Streptomyces coelicolor mutants were constructed that lacked genes identified as the likely candidates for encoding methyl-specific restriction nucleases (the products of the SCO4213, SCO4631 and SCO2863 genes, as well as the SCO3261-SCO3262 operon) that are located in the laterally acquired genomic islands of the S. coelicolor chromosome; these mutants showed partial alleviation of methylated DNA restriction. Cloning of these genes in the close relative Streptomyces lividans increased the restriction of methylated DNA by this species, confirming their role as part of the methyl-specific restriction system of S. coelicolor.