Palmer B R, Marinus M G
Department of Plant and Microbial Sciences, University of Canterbury, Christchurch, New Zealand.
Gene. 1994 May 27;143(1):1-12. doi: 10.1016/0378-1119(94)90597-5.
The construction of a variety of strains deficient in the methylation of adenine and cytosine residues in DNA by the methyltransferases (MTases) Dam and Dcm has allowed the study of the role of these enzymes in the biology of Escherichia coli. Dam methylation has been shown to play a role in coordinating DNA replication initiation, DNA mismatch repair and the regulation of expression of some genes. The regulation of expression of dam has been found to be complex and influenced by five promoters. A role for Dcm methylation in the cell remains elusive and dcm- cells have no obvious phenotype. dam- and dcm- strains have a range of uses in molecular biology and bacterial genetics, including preparation of DNA for restriction by some restriction endonucleases, for transformation into other bacterial species, nucleotide sequencing and site-directed mutagenesis. A variety of assays are available for rapid detection of both the Dam and Dcm phenotypes. A number of restriction systems in E. coli have been described which recognise foreign DNA methylation, but ignore Dam and Dcm methylation. Here, we describe the most commonly used mutant alleles of dam and dcm and the characteristics of a variety of the strains that carry these genes. A description of several plasmids that carry dam gene constructs is also included.
通过甲基转移酶（MTases）Dam和Dcm构建DNA中腺嘌呤和胞嘧啶残基甲基化缺陷的多种菌株，使得对这些酶在大肠杆菌生物学中的作用研究成为可能。已表明Dam甲基化在协调DNA复制起始、DNA错配修复以及某些基因表达调控中发挥作用。已发现dam表达的调控很复杂，且受五个启动子影响。Dcm甲基化在细胞中的作用仍不明确，dcm -细胞没有明显的表型。dam -和dcm -菌株在分子生物学和细菌遗传学中有一系列用途，包括制备用于某些限制内切酶切割的DNA、转化为其他细菌物种、核苷酸测序和定点诱变。有多种检测方法可用于快速检测Dam和Dcm表型。大肠杆菌中已描述了许多识别外源DNA甲基化但忽略Dam和Dcm甲基化的限制系统。在此，我们描述了dam和dcm最常用的突变等位基因以及携带这些基因的多种菌株的特征。还包括了几种携带dam基因构建体的质粒的描述。
