Bale A, d'Alarcao M, Marinus M G
Mutat Res. 1979 Feb;59(2):157-65. doi: 10.1016/0027-5107(79)90153-2.
The phenotypic traits of 7 independently isolated dam mutants of Escherichia coli have been examined. The mutant strains differ from the wildtype in the following respects: (1) decreased DNA adenine methylase activity in vivo and in vitro; (2) a 14--85-fold increase in spontaneous mutability; (3) decreased survival after ultraviolet irradiation; (4) a 10--21-fold increase in spontaneous induction of lambda phage from lysogens; (5) a 3--17-fold increase in the level of recombination; and (6) inviability of double mutants containing dam- and recB- or recC-. Unmethylated fd phage chromosomes are able to replicate normally in dam- mutants. A mutant strain in which the dcm gene is deleted is viable, showing that the dcm gene product is dispensible for growth.
对7株独立分离的大肠杆菌dam突变体的表型特征进行了研究。这些突变菌株在以下方面与野生型不同：（1）体内和体外DNA腺嘌呤甲基化酶活性降低；（2）自发突变率增加14至85倍；（3）紫外线照射后存活率降低；（4）溶原菌中λ噬菌体的自发诱导增加10至21倍；（5）重组水平增加3至17倍；（6）含有dam-和recB-或recC-的双突变体不可存活。未甲基化的fd噬菌体染色体能够在dam-突变体中正常复制。dcm基因缺失的突变菌株是可存活的，这表明dcm基因产物对生长是可有可无的。
