Bender J, Kuo J, Kleckner N
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, Massachusetts 02138.
Genetics. 1991 Aug;128(4):687-94. doi: 10.1093/genetics/128.4.687.
Tn10 and IS10 transpose by a nonreplicative mechanism in which the transposon is excised from the donor molecule and integrated into a target DNA site, leaving behind a break at the original donor site. The fate of this broken donor DNA molecule is not known. We describe here two experiments that address this issue. One experiment demonstrates that a polar IS10 element gives rise to polarity-relief revertants at less than 1% the frequency of transposition of the same element in the same culture. In a second experiment, transpositions of an IS10 element from one site in the bacterial genome to another are selected and the resulting isolates examined for alterations at the donor site; none of 1088 such isolates exhibited a detectable change at the donor locus. These results are compatible with two possible fates of the transposon donor molecule: degradation ("donor suicide"), or restoration of the original information at the donor site by a recombinational repair mechanism analogous to double-strand break repair. These results argue against the possibility that the donor molecule gap is simply resealed by intramolecular rejoining.
Tn10和IS10通过一种非复制机制进行转座，在该机制中，转座子从供体分子上切除并整合到目标DNA位点，在原始供体位点留下一个断裂口。这个断裂的供体DNA分子的命运尚不清楚。我们在此描述两个解决此问题的实验。一个实验表明，一个极性IS10元件产生极性缓解回复子的频率不到同一元件在同一培养物中转座频率的1%。在第二个实验中，选择IS10元件从细菌基因组中的一个位点到另一个位点的转座，并检查所得分离株在供体位点的改变；1088个这样的分离株中没有一个在供体位点表现出可检测到的变化。这些结果与转座子供体分子的两种可能命运相符：降解（“供体自杀”），或通过类似于双链断裂修复的重组修复机制在供体位点恢复原始信息。这些结果反对供体分子缺口简单地通过分子内重新连接重新封闭的可能性。
