质粒RSF 1010寄主范围特性的遗传学分析

GENETIC ANALYSIS OF THE HOST RANGE OF THE PLASMID RSF1O1O

采用 Tn5插入诱变、限制性核酸内切酶作图以及 DNA 转化等方法,对广泛寄主范围型质粒 RSF 1010的衍生体——pKT 240进行研究。证实质粒的寄主围决定于它在遗传背景不同的寄主中复制并保存自身的能力,而 repA,repB 和 repC 基因为该质粒复制所必需。

32 host range mutants of pMO58,whichcontains a 8.0 kb fragment of RSF1010,werescreened,using the transposon Tn5 insertionmutagenesis.To judge the genes which affectthe host range of plasmid,the Tn5 insertionsites were located with restriction endonuc-lease mapping.The ability of the plasmidreplication in different recipients was check-ed with DNA transformation.The results further confirmed the barrierto the host range of plasmid was their inabi-lity to replicate and maintain themselves ingenetically different host.The repA repBand repC genes were necessary for the plasmidreplication,but the repC gene may be a posi-tive regulator and its function may be comple-mented by host gene products.