Novel mutations of Escherichia coli that produce recombinogenic lesions in DNA. V. Recombinogenic plasmids from arl mutants of Escherichia coli are unusually sensitive to nuclease S1 and partially deficient in cytosine methylation at C-C-(A/T)-G-G sequenc
Novel mutations of Escherichia coli that produce recombinogenic lesions in DNA. V. Recombinogenic plasmids from arl mutants of Escherichia coli are unusually sensitive to nuclease S1 and partially deficient in cytosine methylation at C-C-(A/T)-G-G sequenc
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大肠杆菌的新突变可在 DNA 中产生重组损伤。
DOI：
10.1016/0022-2836(82)90231-5
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发表时间：
1982
影响因子：
5.6
通讯作者：
Hays,JB
中科院分区：
文献类型：
--
作者：
Korba,BE;Hays,JB
细菌上生长的λ噬菌体(ARL−噬菌体)的特性已经最完全地定义了以前与大肠杆菌Ar突变相关的两种新表型，即基因重组频率的增加和DNA对单链特异性核酸酶S1的异常敏感性。我们现在发现，在ARL−突变体(ARL−质粒)中保持的质粒具有较高的重组频率，对核酸酶S1异常敏感(在有限的区域)，以及一种新的ARL表型，即C-C-(A/T)-G-G序列内胞嘧啶部分缺失甲基化。各种ARL DNA质粒(所有pBR322衍生物)通过三种不同的检测(同源和异源多聚体的频率，分子内重组的效率)显示出更高的重组(4-10倍)。细菌的质粒(转化为线型后)被核酸酶S1切割约0.7次/双链；ARL+质粒对核酸酶S1具有抗性。限制性内切酶EcoRII(识别序列，C-C-(A/T)-G-G)比ARL+−更容易切割ARL-−质粒，但ARL-−质粒仍比DCMDNA更具EcoRII抗性。Colidcm突变体，缺乏染色体胞嘧啶甲基酶；识别序列，也C-C-(A/T)-G-G)。经层析分析，ARL-−的5-甲基胞嘧啶含量低于ARL+(0.07%比0.15%)。虽然6-甲基腺嘌呤的含量相同(0.5mol%)。
Two novel phenotypes previously associated witharlmutations ofEscherichia coli, increased frequencies of genetic recombination and unusual sensitivity of DNA to the single-strand-specific nuclease S1, have been defined most completely by the properties of λ bacteriophages grown onarlbacteria (Arl−phages). We now find that plasmids maintained inarlmutants (Arl−plasmids) exhibit elevated recombination frequencies, unusual sensitivity to nuclease S1(in a limited number of regions) and a new Arl phenotype, partially deficient methylation of the inner cytosine at C-C-(A/T)-G-G sequences.A variety of Arl−plasmids (all pBR322 derivatives) show elevated recombination (4 to 10-fold) by three different assays (frequencies of homomultimers and of heteromultimers, efficiency of intramolecular recombination). Plasmids fromarlbacteria (after conversion to linear form) are nicked by nuclease S1about 0.7 times per duplex; Arl+plasmids are nuclease S1-resistant. Restriction endonucleaseEcoRII (recognition sequence, C-C-(A/T)-G-G) cuts Arl−plasmid DNA more readily than Arl+DNA, but Arl−plasmids are still moreEcoRII-resistant than Dcm−plasmids (fromE. coli dcmmutants, which lack the chromosomal cytosine methylase; recognition sequence, also C-C-(A/T)-G-G). By chromatographic analyses, Arl−plasmid DNA contains less 5-methylcytosine than Arl+(0.07%versus0.15%). although the 6-methyladenine content is the same (0.5mol%).