García L R, Molineux I J
Department of Microbiology, University of Texas, Austin 78712-1095, USA.
J Bacteriol. 1995 Jul;177(14):4077-83. doi: 10.1128/jb.177.14.4077-4083.1995.
The penetration of bacteriophage T7 DNA into F plasmid-containing Escherichia coli cells was determined by measuring Dam methylation of the entering genome. T7 strains that cannot productively infect F-containing cells fail to completely translocate their DNA into the cell before the infection aborts. The entry of the first 44% of the genome occurs normally in an F-containing cell, but the entry of the remainder is aberrant. Bypassing the normal mode of entry of the T7 genome by transfecting naked DNA into competent cells fails to suppress F exclusion of phage development. However, overexpression of various nontoxic T7 1.2 alleles from a high-copy-number plasmid or expression of T3 1.2 from a T7 genome allows phage growth in the presence of F.
通过测量进入的基因组的Dam甲基化来确定噬菌体T7 DNA进入含F质粒的大肠杆菌细胞的情况。不能有效感染含F细胞的T7菌株在感染中止前无法将其DNA完全转运到细胞内。基因组前44%的进入在含F细胞中正常发生,但其余部分的进入则异常。通过将裸DNA转染到感受态细胞中来绕过T7基因组的正常进入模式,无法抑制噬菌体发育的F排斥。然而,从高拷贝数质粒中过表达各种无毒的T7 1.2等位基因或从T7基因组中表达T3 1.2,可使噬菌体在有F存在的情况下生长。