Substrate-Dependent Millisecond Domain Motions in DNA Polymerase 尾

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• 作者：Rebecca B. Berlow¹ ; ¹ ; ^&dagger ; ; Monalisa Swain² ; ^&dagger ; ; Shibani Dalal³ ; Joann B. Sweasy³ ; ^{joann.sweasy@yale.edu} ; J. Patrick Loria¹ ; ² ; ^{patrick.loria@yale.edu}
• 关键词：DNA polymerase 尾 ; solution NMR ; conformational change ; relaxation dispersion ; enzyme motions
• 刊名：Journal of Molecular Biology
• 出版年：2012
• 期刊代码：102_00222836
• 类别：imm
• 出版时间：8 June, 2012
• 卷：419
• 期：3-4
• 页码：171-182
• 文件大小：1781 K

摘要

DNA polymerase 尾 (Pol 尾) is a 聽39-kDa enzyme that performs the vital cellular function of repairing damaged DNA. Mutations in Pol 尾 have been linked to various cancers, and these mutations are further correlated with altered Pol 尾 enzymatic activity. The fidelity of correct nucleotide incorporation into damaged DNA is essential for Pol 尾 repair function, and several studies have implicated conformational changes in Pol 尾 as a determinant of this repair fidelity. In this work, the rate constants for domain motions in Pol 尾 have been determined by solution NMR relaxation dispersion for the apo and substrate-bound, binary forms of Pol 尾. In apo Pol 尾, molecular motions, primarily isolated to the DNA lyase domain, are observed to occur at 聽1400聽s^鈭?#xA0;1. Additional analysis suggests that these motions allow apo Pol 尾 to sample a conformation similar to the gapped DNA-substrate-bound form. Upon binding DNA, these lyase domain motions are significantly quenched, whereas evidence for conformational motions in the polymerase domain becomes apparent. These NMR studies suggest an alteration in the dynamic landscape of Pol 尾 due to substrate binding. Moreover, a number of the flexible residues identified in this work are also the location of residues, which upon mutation lead to cancer phenotypes in vivo, which may be due to the intimate role of protein motions in Pol 尾 fidelity.