Inverted repeats as genetic elements for promoting DNA inverted duplication: implications in gene amplification
Inverted repeats as genetic elements for promoting DNA inverted duplication: implications in gene amplification
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DOI：
10.1093/nar/29.17.3529
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发表时间：
2001-09-01
影响因子：
14.9
通讯作者：
Whang-Peng, J
中科院分区：
文献类型：
--
作者：
Lin, CT;Lin, WH;Whang-Peng, J
反向重复序列是基因组不稳定性的重要遗传因素。在目前的研究中，我们已经调查的作用，反向重复序列的DNA重排反应中使用线性DNA基板。我们表明，末端反向重复的线性DNA底物可以有效地转化大肠杆菌。转化产物含有环状反向二聚体，其中末端反向重复序列之间的DNA序列是重复的。与环状DNA底物的重组/重排产物（其仅是反向二聚体的一种特定形式）相反，线性DNA底物的重排产物由反向二聚体的两种异构形式组成。大肠杆菌突变体缺陷的RecBCD表现出大大降低的转化效率，这表明RecBCD的作用，而不是破坏这些线性DNA底物的保护。这些结果表明了一种模型，其中双链断裂末端附近的反向重复序列可以通过解旋酶/核酸外切酶加工以形成发夹帽。发夹加帽的DNA中间体的加工然后可以产生反向重复。含有末端反向重复序列的线性DNA底物也可以在COS细胞中转化为反向二聚体，表明这种类型的基因组不稳定性从细菌到哺乳动物细胞都是保守的。
Inverted repeats are important genetic elements for genome instability. In the current study we have investigated the role of inverted repeats in a DNA rearrangement reaction using a linear DNA substrate. We show that linear DNA substrates with terminal inverted repeats can efficiently transform Escherichia coli. The transformation products contain circular inverted dimers in which the DNA sequences between terminal inverted repeats are duplicated. In contrast to the recombination/rearrangement product of circular DNA substrates, which is exclusively one particular form of the inverted dimer, the rearrangement products of the linear DNA substrate consist of two isomeric forms of the inverted dimer. Escherichia coli mutants defective in RecBCD exhibit much reduced transformation efficiency, suggesting a role for RecBCD in the protection rather than destruction of these linear DNA substrates. These results suggest a model in which inverted repeats near the ends of a double-strand break can be processed by a helicase/exonuclease to form hairpin caps. Processing of hairpin capped DNA intermediates can then yield inverted duplications. Linear DNA substrates containing terminal inverted repeats can also be converted into inverted dimers in COS cells, suggesting conservation of this type of genome instability from bacteria to mammalian cells.