Loss of plasmids containing cloned inserts coding for novobiocin resistance or novobiocin sensitivity in Haemophilus influenzae
Loss of plasmids containing cloned inserts coding for novobiocin resistance or novobiocin sensitivity in Haemophilus influenzae
复制标题
流感嗜血杆菌中含有编码新生霉素抗性或新生霉素敏感性的克隆插入片段的质粒丢失
DOI：
10.1128/jb.158.3.872-877.1984
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发表时间：
1984
影响因子：
3.2
通讯作者：
M. Ledbetter
中科院分区：
文献类型：
--
作者：
J. Setlow;D. Spikes;M. Ledbetter
分别编码新生霉素抗性和敏感性的质粒pNov 1和pNov 1 s很容易从野生型流感嗜血杆菌中丢失，但保留在缺乏可诱导缺陷原噬菌体的菌株中。质粒丢失可以通过质粒中的低拷贝数突变或宿主染色体中某些抗生素抗性标记的存在而部分或全部消除。当质粒存在时，噬菌体HP 1c 1（通过噬菌斑试验测量）和缺陷噬菌体（通过电子显微镜测量）的释放都会增加。pNov 1和染色体之间的重组频率，导致质粒转化为pNov 1 s，在某些情况下可以通过染色体中卡那霉素抗性标记的存在从正常的60 - 70%降低到10%以下。这表明由质粒编码的基因产物（其表达受卡那霉素抗性标记的影响）是高重组频率的原因。从体外实验中获得的证据表明，该基因产物是一种促旋酶。
Plasmids pNov1 and pNov1s , coding for resistance and sensitivity to novobiocin, respectively, were readily lost from wild-type Haemophilus influenzae but retained in a strain lacking an inducible defective prophage. The plasmid loss could be partly or wholly eliminated by a low-copy-number mutation in the plasmid or by the presence of certain antibiotic resistance markers in the host chromosome. Release of both phage HP1c1 , measured by plaque assay, and defective phage, measured by electron microscopy, was increased when the plasmids were present. The frequency of recombination between pNov1 and the chromosome, causing the plasmid to be converted to pNov1s , could under some circumstances be decreased from the normal 60 to 70% to below 10% by the presence of a kanamycin resistance marker in the chromosome. This suggested that a gene product coded for by the plasmid, the expression of which was affected by the kanamycin resistance marker, was responsible for the high recombination frequency. Evidence was obtained from in vitro experiments that the gene product was a gyrase.