Boyd A C, Archer J A, Sherratt D J
Department of Molecular Biology, University of Edinburgh, UK.
Mol Gen Genet. 1989 Jun;217(2-3):488-98. doi: 10.1007/BF02464922.
A third of the 6.6 kb genome of ColE1 is devoted to mobilization (mob) genes necessary to promote its specific transfer in the presence of conjugative plasmids. The mob region is genetically complex: two mob genes are entirely overlapped by a third. Oligonucleotide-directed mutagenesis was used to insert an amber codon into one of the overlapped genes and make possible a full complementation analysis of mob. Four mob genes essential for mobilization by R64drd11 were thus identified. Fragments of mob were subcloned under control of the Ptac promoter in a suitable vector, overexpressed in minicells and the mobilization proteins visualized. A comprehensive alignment of the mob region of ColE1 with those of its close relatives ColK and ColA demonstrating that the four essential mob genes are conserved is also presented.
大肠杆菌质粒ColE1的6.6 kb基因组中有三分之一用于移动（mob）基因，这些基因在接合质粒存在时促进其特异性转移所必需。mob区域在遗传上很复杂：两个mob基因完全被第三个基因重叠。使用寡核苷酸定向诱变将琥珀密码子插入其中一个重叠基因中，从而对mob进行全面的互补分析。由此鉴定出了四个对R64drd11介导的转移至关重要的mob基因。将mob片段亚克隆到合适载体中Ptac启动子的控制下，在微小细胞中过表达，并观察到移动蛋白。还展示了ColE1的mob区域与其近亲ColK和ColA的mob区域的全面比对，表明这四个必需的mob基因是保守的。
