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首页> 外文期刊>Molecular and Cellular Biology >Involvement of single-stranded tails in homologous recombination of DNA injected into Xenopus laevis oocyte nuclei.
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Involvement of single-stranded tails in homologous recombination of DNA injected into Xenopus laevis oocyte nuclei.

机译：单链尾巴参与注入非洲爪蟾卵母细胞核的DNA的同源重组。

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Homologous recombination of DNA molecules injected into Xenopus laevis oocyte nuclei is extremely efficient when those molecules are linear and have overlapping homologous ends. It was previously shown that a 5'----3' exonuclease activity in oocytes attacks injected linear DNAs and leaves them with single-stranded 3' tails. We tested the hypothesis that such tailed molecules are early intermediates on the pathway to recombination products. Substrates with 3' tails were made in vitro and injected into oocytes, where they recombined rapidly and efficiently. In experiments with mixed substrates, molecules with 3' tails entered recombination intermediates and products more rapidly than did molecules with flush ends. Molecules endowed in vitro with 5' tails also recombined efficiently in oocytes, but their rate was not faster than for flush-ended substrates. In most cases, the 5' tails served as templates for resynthesis of the 3' strands, regenerating duplex ends which then entered the normal recombination pathway. In oocytes from one animal, some of the 5' tails were removed, and this was exacerbated when resynthesis was partially blocked. Analysis by two-dimensional gel electrophoresis of recombination intermediates from 5'-tailed substrates confirmed that they had acquired 3' tails as a result of the action of the 5'----3' exonuclease. These results demonstrate that homologous recombination in oocytes proceeds via a pathway that involves single-stranded 3' tails. Molecular models incorporating this feature are discussed.
机译：当注射到非洲爪蟾卵母细胞核中的DNA分子是线性且具有重叠的同源末端时，它们的同源重组非常有效。先前已证明卵母细胞中的5'---- 3'核酸外切酶活性会攻击注入的线性DNA，并使它们留下单链3'尾巴。我们测试了这样的假说，即这种拖尾的分子是重组产物途径中的早期中间体。具有3'尾巴的底物是在体外制备的，并注入卵母细胞中，在那里它们可以快速有效地重组。在具有混合底物的实验中，具有3'尾巴的分子比具有齐平末端的分子进入重组中间产物的速度更快。体外具有5'尾巴的分子在卵母细胞中也能有效重组，但其速率并不比齐平底物快。在大多数情况下，5'尾巴用作3'链再合成的模板，再生双链体末端，然后进入正常的重组途径。在一只动物的卵母细胞中，一些5'尾巴被去除，当再合成被部分阻止时，这种情况会加剧。通过二维凝胶电泳对来自5'尾底物的重组中间体进行分析，证实了由于5'---- 3'核酸外切酶的作用，它们获得了3'尾巴。这些结果表明，卵母细胞中的同源重组通过涉及单链3'尾巴的途径进行。讨论了包含此功能的分子模型。

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