Ultrafast Water Dynamics at the Interface of the Polymerase鈥揇NA Binding Complex

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• 作者：Yi Yang ; Yangzhong Qin ; Qing Ding ; Marina Bakhtina ; Lijuan Wang ; Ming-Daw Tsai ; Dongping Zhong
• 刊名：Biochemistry
• 出版年：2014
• 出版时间：August 26, 2014
• 年：2014
• 卷：53
• 期：33
• 页码：5405-5413
• 全文大小：657K
• ISSN：1520-4995

文摘

DNA polymerases slide on DNA during replication, and the interface must be mobile for various conformational changes. The role of lubricant interfacial water is not understood. In this report, we systematically characterize the water dynamics at the interface and in the active site of a tight binding polymerase (pol 尾) in its binary complex and ternary state using tryptophan as a local optical probe. Using femtosecond spectroscopy, we observed that upon DNA recognition the surface hydration water is significantly confined and becomes bound water at the interface, but the dynamics are still ultrafast and occur on the picosecond time scale. These interfacial water molecules are not trapped but are mobile in the heterogeneous binding nanospace. Combining our findings with our previous observation of ultrafast water motions at the interface of a loose binding polymerase (Dpo4), we conclude that the binding interface is dynamic and the water molecules in various binding clefts, channels, and caves are mobile and even fluid with different levels of mobility for loose or tight binding polymerases. Such a dynamic interface should be general to all DNA polymerase complexes to ensure the biological function of DNA synthesis.