Pshennikova E S, Kolot M N, Vorob'eva I P, Lipasova V A, Khmel' I A
Genetika. 1985 Apr;21(4):541-7.
To study the localization and expression of the ColIb-P9 plasmid genes responsible for colicin Ib synthesis and immunity to it, we isolated a series of Tn5 insertion mutants of recombinant plasmid pIV41 containing the colicin Ib gene in EcoRI fragment of ColIb-P9 (2.7 kb) and the deletion plasmid carrying only a part of the colicin gene. The direction of colicin Ib gene transcription was determined by the analysis of the polypeptides synthesized in minicells carrying the mutant plasmids. The pIV41 plasmid containing cells have been shown to be resistant to both colicin Ib and Ia activities. This type of resistance is usually associated with chromosomal mutations resulting in loss of cell receptors for colicin Ib adsorption. Apparently, the EcoRI fragment of ColIb-P9 studied contains no gene responsible for immunity to colicin. It has been shown that this gene is a portion of SalI fragment (22 kb) of the ColIb-P9, the fragment also carrying the gene which mediates synthesis of colicin Ib.
为了研究负责大肠杆菌素Ib合成及其免疫性的ColIb - P9质粒基因的定位和表达，我们分离了一系列重组质粒pIV41的Tn5插入突变体，该重组质粒在ColIb - P9的EcoRI片段（2.7 kb）中含有大肠杆菌素Ib基因，以及仅携带部分大肠杆菌素基因的缺失质粒。通过分析携带突变体质粒的小细胞中合成的多肽，确定了大肠杆菌素Ib基因的转录方向。已证明含有pIV41质粒的细胞对大肠杆菌素Ib和Ia活性均具有抗性。这种抗性类型通常与染色体突变有关，导致细胞失去大肠杆菌素Ib吸附的受体。显然，所研究的ColIb - P9的EcoRI片段不包含负责对大肠杆菌素免疫的基因。已证明该基因是ColIb - P9的SalI片段（22 kb）的一部分，该片段还携带介导大肠杆菌素Ib合成的基因。
