Dynamic DNA binding, junction recognition and G4 melting activity underlie the telomeric and genome-wide roles of human CST.
Dynamic DNA binding, junction recognition and G4 melting activity underlie the telomeric and genome-wide roles of human CST.
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DOI：
10.1093/nar/gkx878
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发表时间：
2017-12-01
影响因子：
14.9
通讯作者：
Price CM
中科院分区：
文献类型：
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作者：
Bhattacharjee A;Wang Y;Diao J;Price CM
人类 CST (CTC1–STN1–TEN1) 是一种 ssDNA 结合复合物，有助于解决端粒和全基因组范围内的复制问题。 CST 与复制蛋白 A (RPA) 相似，因为这两种复合物具有相似的 OB 折叠阵列，并且具有结构相似的小亚基。然而，CST 和 RPA 的整体架构和功能是不同的。目前，CST 在各种复制问题上发挥作用的机制仍不清楚。为了阐明 CST 机制，我们检查了 CST 结合和解析在 CST 活性位点发现的 DNA 结构的能力。我们发现 CST 优先结合 ss-dsDNA 连接，这种活性可以解释端粒酶作用后端粒 C 链合成的增量性质。我们还表明，CST 展开 G 四链体结构，从而为 CST 提供一种机制，以促进通过端粒和其他富含 GC 的区域进行复制。最后，smFRET 分析表明，CST 与 ssDNA 的结合是动态的，CST 复合物经历浓度依赖性自我位移。这些发现支持基于 RPA 的模型，其中单个 OB 折叠的解离和重新关联允许 CST 介导伙伴蛋白的加载和卸载，以促进端粒复制的各个方面和复制应激的全基因组分辨率。
Human CST (CTC1–STN1–TEN1) is a ssDNA-binding complex that helps resolve replication problems both at telomeres and genome-wide. CST resembles Replication Protein A (RPA) in that the two complexes harbor comparable arrays of OB-folds and have structurally similar small subunits. However, the overall architecture and functions of CST and RPA are distinct. Currently, the mechanism underlying CST action at diverse replication issues remains unclear. To clarify CST mechanism, we examined the capacity of CST to bind and resolve DNA structures found at sites of CST activity. We show that CST binds preferentially to ss-dsDNA junctions, an activity that can explain the incremental nature of telomeric C-strand synthesis following telomerase action. We also show that CST unfolds G-quadruplex structures, thus providing a mechanism for CST to facilitate replication through telomeres and other GC-rich regions. Finally, smFRET analysis indicates that CST binding to ssDNA is dynamic with CST complexes undergoing concentration-dependent self-displacement. These findings support an RPA-based model where dissociation and re-association of individual OB-folds allow CST to mediate loading and unloading of partner proteins to facilitate various aspects of telomere replication and genome-wide resolution of replication stress.
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影响因子：
4.7
作者：
Churikov D;Corda Y;Luciano P;Géli V
通讯作者：
Géli V
影响因子：
3.7
作者：
Gibb B;Ye LF;Gergoudis SC;Kwon Y;Niu H;Sung P;Greene EC
通讯作者：
Greene EC
影响因子：
4.5
作者：
Bhattacharjee A;Stewart J;Chaiken M;Price CM
通讯作者：
Price CM
影响因子：
16.8
作者：
Arnoult N;Karlseder J
通讯作者：
Karlseder J
影响因子：
14.8
作者：
通讯作者：
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