Waggoner B T, Pato M L
J Virol. 1978 Sep;27(3):587-94. doi: 10.1128/JVI.27.3.587-594.1978.
To determine whether the early replication of Mu prophage DNA proceeds beyond the termini of the prophage into hose DNA, the amounts of both Mu DNA and the prophage-adjacent host DNA sequences were measured using a DNA-DNA annealing assay after induction of the Mu vegetative cycle. Whereas Mu-specific DNA synthesis began 6 to 8 min after induction, no amplification of the adjacent DNA sequences was observed. These data suggest that early Mu-induced DNA synthesis is constrained within the boundaries of the Mu prophage. Since prophage Mu DNA does not undergo a prophage lambda-like excision from its original site after induction (E. Ljungquist and A. I. Bukhari, Proc. Natl. Acad. Sci. U.S.A. 74:3143--3147, 1977), we propose the existence of a control mechanism which excludes prophage-adjacent sequences from the initial mu prophage replication. The frequencies of the Mu prophage-adjacent DNA sequences, relative to other Escherichia coli genes, were not observed to change after the onset of Mu-specific DNA replication. This suggests that these regions remain associated with the host chromosome and continue to be replicated by the chromosomal replication fork. Therefore, we conclude that both the Mu prophage and adjacent host sequences are maintained in the host chromosome, rather than on an extrachromosomal form containing Mu and host DNA.
为了确定Mu原噬菌体DNA的早期复制是否会超出原噬菌体的末端进入宿主DNA，在诱导Mu营养周期后，使用DNA-DNA退火试验测量了Mu DNA和原噬菌体相邻的宿主DNA序列的量。虽然Mu特异性DNA合成在诱导后6至8分钟开始，但未观察到相邻DNA序列的扩增。这些数据表明，早期Mu诱导的DNA合成被限制在Mu原噬菌体的边界内。由于原噬菌体Mu DNA在诱导后不会从其原始位点进行类似噬菌体λ的切除（E. Ljungquist和A. I. Bukhari，《美国国家科学院院刊》74:3143 - 3147，1977），我们提出存在一种控制机制，该机制在Mu原噬菌体的初始复制中排除原噬菌体相邻序列。相对于其他大肠杆菌基因，未观察到Mu原噬菌体相邻DNA序列的频率在Mu特异性DNA复制开始后发生变化。这表明这些区域仍与宿主染色体相关联，并继续由染色体复制叉进行复制。因此，我们得出结论，Mu原噬菌体和相邻的宿主序列都保留在宿主染色体中，而不是存在于包含Mu和宿主DNA的染色体外形式上。
