Figure 7-5: Chromosomal insertion of phage Mu-1 DNA by a transposition mechanism. In the virion, Mu-1 DNA is attached to host DNA at both ends-less than 100bp on the left, and about 2 kb on the right. Any part of the chromosome can be used as target. The first step of transposition is strand transfer, where the 3' ends of Mu are ligated to opposite strands of target DNA 5bp apart, leaving free 3' ends of the chromosomal DNA and free 5' ends of the host DNA from the virion. The strand transfer product is redrawn in the next line for ease of visualization. Repair synthesis initiated from the 3' ends of target DNA fill the gap, the host DNA that entered from the virion is trimmed off, and the target DNA 3' ends are ligated to the 5' Mu-1 ends. Mu-1 can also undergo replicative transposition; where the donor DNA is not trimmed and the transposon is replicated; however, this is only fruitful with a circular donor and does not occur in the initial transposition from linear virion DNA. (for better image quality, click here for tif image, which may be quite large; may also require screen refreshing plus special software to view; or view larger tif in separate window)

Figure 7-1, Figure 7-2, Figure 7-3, Figure 7-4, Figure 7-5, Figure 7-6, Figure 7-7, Figure 7-8

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