Recombination between two TnA transposon sequences oriented as inverse repeats is found less frequently than between direct repeats |
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Authors: | S J Chiang R C Clowes |
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Institution: | (1) The University of Texas at Dallas, P.O. Box 688, 75080 Richardson, Texas, USA;(2) Present address: Department of Microbiology, The Medical Center, University of Alabama in Birmingham, 35294 Birmingham, Alabama, USA |
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Abstract: | Summary Inverse repeats of the transposon Tn2660 in either a ColEl or an R6K replicon, with or without inversions of the parental DNA sequences between the repeats, show no detectable (<2%) evidence of recombination between the repeats after 60 generations of growth in either recA or recA
+ hosts. In contrast, attempts made to construct plasmids which carry two direct repeats by in vitro cleavage and ligation in a recA host were unsuccessful, although homologous plasmids with inverse repeats could be constructed, and other plasmids were found consistent with products of recombination between the direct repeats of a transient intermediate structure. It is concluded that in recA or recA
+ hosts recombination between direct repeats of a transposon is frequent, whereas recombination between inverse repeats of a homologous structure has not been observed. A model to explain this difference depends upon a mechanism that produces a nick in only one of the pair of strands at the internal resolution site (IRS) sequence of the transposon. |
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