Bukhari A I, Froshauer S
Gene. 1978 Jul;3(4):303-14. doi: 10.1016/0378-1119(78)90040-9.
We have isolated mutants of bacteriophage Mu carrying the X mutations caused by the insertion of cam (Tn9), a transposon for chloramphenicol resistance. The Mu X cam mutants were obtained by selecting for heat-resistant survivors of a Mucts62, P1cam dilysogen. Like the previously described X mutants, Mu X cam mutants are defective prophages which can be excised from the host DNA at a frequency of 10(-5) to 10(-7) per cell. Tn9 insertions in Mu X cam mutants are located within 5000 base pairs of the left end of Mu DNA in a region that controls early replication functions of Mu. There is one EcoRI cleavage site in Tn9. The Tn9 transposon itself can be excised precisely from the Mu X cam mutants to generate wild type Mu. In most Mu X cam mutants, precise excision of Tn9 occurs at a low frequency (10(-6) per cell), whereas in some, the frequency is higher (10(-4) per cell). Mu X cam prophages can replicate after induction with the help of wild type Mu. The lysates containing Mu X cam particles, however, fail to transduce chloramphenicol resistance at a high frequency; Mu X cam mutants apparently have a cis dominant defect in integration.
我们分离出了携带由cam（Tn9）插入引起的X突变的噬菌体Mu突变体，cam是一种赋予氯霉素抗性的转座子。通过筛选Mucts62、P1cam双溶原菌的耐热存活菌获得了Mu X cam突变体。与先前描述的X突变体一样，Mu X cam突变体是有缺陷的原噬菌体，其可以以每个细胞10^(-5)至10^(-7)的频率从宿主DNA中切除。Mu X cam突变体中的Tn9插入位于Mu DNA左端5000个碱基对内的一个控制Mu早期复制功能的区域。Tn9中有一个EcoRI切割位点。Tn9转座子本身可以从Mu X cam突变体中精确切除以产生野生型Mu。在大多数Mu X cam突变体中，Tn9的精确切除以低频率（每个细胞10^(-6)）发生，而在一些突变体中，频率较高（每个细胞10^(-4)）。Mu X cam原噬菌体在野生型Mu的帮助下诱导后可以复制。然而，含有Mu X cam颗粒的裂解物不能高频转导氯霉素抗性；Mu X cam突变体显然在整合方面有顺式显性缺陷。
