5′ to 3′ Unfolding Directionality of DNA Secondary Structures by Replication Protein A G-QUADRUPLEXES AND DUPLEXES
5′ to 3′ Unfolding Directionality of DNA Secondary Structures by Replication Protein A G-QUADRUPLEXES AND DUPLEXES
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DOI：
10.1074/jbc.m115.709667
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发表时间：
2016-09-30
影响因子：
4.8
通讯作者：
Saintome, Carole
中科院分区：
文献类型：
--
作者：
Safa, Layal;Gueddouda, Nassima Meriem;Saintome, Carole
复制蛋白A（RPA）是一种单链DNA结合蛋白，在DNA代谢中起重要作用。RPA能够展开端粒DNA序列形成的G-四链体（G4）结构，这是端粒维持的重要功能。为了阐明RPA展开端粒G4的机制，我们研究了其与采用G4结构的寡核苷酸的相互作用，所述G4结构在G4的两侧延伸有单链尾。使用几种生物化学和生物物理方法，并在特定的G4配体，如端粒和360 A的存在下，其特征在于结合和展开。我们的数据显示RPA可以结合在G4的每一侧，但它只能从5'向3'解开G4。我们用hRPA亚基沿沿着单链DNA的5'至3'方向排列来解释5'至3'方向的解折叠。此外，我们通过动力学实验证明，RPA进行双链体展开具有相同的方向性。
The replication protein A (RPA) is a single-stranded DNA-binding protein that plays an essential role in DNA metabolism. RPA is able to unfold G-quadruplex (G4) structures formed by telomeric DNA sequences, a function important for telomere maintenance. To elucidate the mechanism through which RPA unfolds telomeric G4s, we studied its interaction with oligonucleotides that adopt a G4 structure extended with a single-stranded tail on either side of the G4. Binding and unfolding was characterized using several biochemical and biophysical approaches and in the presence of specific G4 ligands, such as telomestatin and 360A. Our data show that RPA can bind on each side of the G4 but it unwinds the G4 only from 5' toward 3'. Weexplain the 5' to 3' unfolding directionality in terms of the 5' to 3' oriented laying out of hRPA subunits along single-stranded DNA. Furthermore, we demonstrate by kinetics experiments that RPA proceeds with the same directionality for duplex unfolding.