Interaction of the Zα domain of human ADAR1 with a negatively supercoiled plasmid visualized by atomic force microscopy
Interaction of the Zα domain of human ADAR1 with a negatively supercoiled plasmid visualized by atomic force microscopy
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DOI：
10.1093/nar/gkh810
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发表时间：
2004-01-01
影响因子：
14.9
通讯作者：
Lyubchenko, YL
中科院分区：
文献类型：
--
作者：
Lushnikov, AY;Brown, BA;Lyubchenko, YL
最近，人们对左手DNA构象的兴趣因发现许多蛋白质含有Zalpha结构域而增加，Zalpha结构域已被证明特异性识别Z-DNA。Zalpha的生物学功能目前尚不清楚，但有人认为它可能特异性地指导由负超螺旋诱导的Z-DNA的蛋白质区域活跃转录基因。许多研究，包括与Z-DNA复合的晶体结构，都集中在人类ADAR 1 Zalpha结构域上。我们假设Zalpha（ADAR 1）结构域对Z-DNA序列的识别是环境特异性的，发生在能量条件下，有利于Z-DNA的形成。为了验证这一假设，我们应用原子力显微镜图像Zalpha（ADAR 1）与超螺旋质粒DNA复合。我们已经证明，Zalpha（ADAR 1）特异性结合Z-DNA，并优先与d（CG）（n）插入，这需要更少的能量Z-DNA诱导相比，其他序列。一个值得注意的发现是，当DNA超螺旋不足以诱导Z-DNA形成时，观察到位点特异性Zalpha与d（GC）（13）或d（GC）（2）C（GC）（10）插入片段结合。这些结果表明，Zalpha（ADAR 1）的结合设施的B到Z的过渡，并提供了额外的支持模型，Z-DNA结合蛋白可能通过结构特异性识别调节生物过程。
Interest to the left-handed DNA conformation has been recently boosted by the findings that a number of proteins contain the Zalpha domain, which has been shown to specifically recognize Z-DNA. The biological function of Zalpha is presently unknown, but it has been suggested that it may specifically direct protein regions of Z-DNA induced by negative supercoiling in actively transcribing genes. Many studies, including a crystal structure in complex with Z-DNA, have focused on the human ADAR1 Zalpha domain in isolation. We have hypothesized that the recognition of a Z-DNA sequence by the Zalpha(ADAR1) domain is context specific, occurring under energetic conditions, which favor Z-DNA formation. To test this hypothesis, we have applied atomic force microscopy to image Zalpha(ADAR1) complexed with supercoiled plasmid DNAs. We have demonstrated that the Zalpha(ADAR1) binds specifically to Z-DNA and preferentially to d(CG)(n) inserts, which require less energy for Z-DNA induction compared to other sequences. A notable finding is that site-specific Zalpha binding to d(GC)(13) or d(GC)(2)C(GC)(10) inserts is observed when DNA supercoiling is insufficient to induce Z-DNA formation. These results indicate that Zalpha(ADAR1) binding facilities the B-to-Z transition and provides additional support to the model that Z-DNA binding proteins may regulate biological processes through structure-specific recognition.