Selective recognition of pyrimidine motif triplexes by a protein encoded by the bacterial transposon Tn7.
Selective recognition of pyrimidine motif triplexes by a protein encoded by the bacterial transposon Tn7.
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细菌转座子 Tn7 编码的蛋白质选择性识别嘧啶基序三链体。
DOI：
10.1006/jmbi.2001.4553
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Craig,NL
中科院分区：
文献类型：
--
作者：
Rao,JE;Craig,NL
细菌转座子Tn7以其靶向能力在移动遗传元件中有所区别。最近，我们报道了Tn7能够选择性地插入邻近的三螺旋DNA。Tn7编码蛋白TnsC与三联体DNA靶标的结合导致Tn7与分子间和分子内嘧啶基序三联体相邻的特异性转位。在这里，我们进一步探讨Tn7如何靶向三联体DNA。我们报道TnsC区分不同类型的三联体，表现出对嘧啶的结合偏好，而不是嘌呤基序分子间三联体DNA。通过将三聚体形成的寡核苷酸退火至质粒dna，获得了TnsC和Tn7插入谱的结合偏好。虽然补骨脂素的存在不是靶向所必需的，也不是单独能够吸引TnsC，但我们表明补骨脂素在嘧啶基序三联体中的位置确实改变了Tn7插入相对于三联体的位置。三联体靶向途径与tn7编码蛋白TnsD与独特位点attTn7结合介导的高度位点特异性靶向途径的比较表明，TnsC识别每个靶DNA内相似的结构特征，导致位点特异性转位。这项工作表明，参与靶向和调节Tn7易位的原核蛋白TnsC可以选择性地识别嘧啶基序三联体。
The bacterial transposon Tn7 is distinguished among mobile genetic elements by its targeting abilities. Recently, we reported that Tn7 is able to selectively insert adjacent to triple-helical DNA. The binding of TnsC, a Tn7-encoded protein, to the triplex DNA target leads to the specific transposition of Tn7 adjacent to both inter- and intramolecular pyrimidine motif triplexes. Here, we further probe how Tn7 targets triplex DNA. We report that TnsC discriminates between different types of triplexes, showing binding preference for pyrimidine but not for purine motif intermolecular triplex DNA. The binding preferences of TnsC and the Tn7 insertion profiles were obtained using psoralenated, triplex-forming oligonucleotides annealed to plasmid DNAs. Although the presence of psoralen is not required for targeting nor is it alone able to attract TnsC, we show that the location of psoralen within the pyrimidine motif triplex does alter the position of Tn7 insertion relative to the triplex. Comparison between the triplex-targeting pathway and the highly site-specific targeting pathway mediated by the binding of the Tn7-encoded protein, TnsD, to the unique site attTn7, suggests that similar structural features within each target DNA are recognized by TnsC, leading to site-specific transposition. This work demonstrates that a prokaryotic protein involved in the targeting and regulation of Tn7 translocation, TnsC, can selectively recognize pyrimidine motif triplexes.