Dextraze Marie-Eve, Cecchini Sylvain, Bergeron François, Girouard Sonia, Turcotte Kathleen, Wagner J Richard, Hunting Darel J
Center for Research in Radiotherapy (CR2), Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Universite de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4.
Biochemistry. 2009 Mar 10;48(9):2005-11. doi: 10.1021/bi801684t.
Interstrand cross-links impede critical cellular processes such as transcription and replication and are thus considered to be one of the most toxic types of DNA damage. Although several studies now point to the existence of gamma-radiation-induced cross-links in cellular DNA, little is known about the characteristics required for their creation. Recently, we reported the formation of interstrand cross-links that were specific for mismatched nucleotides within 5-bromo-2'-deoxyuridine-substituted DNA. Given the structural specificity for interstrand cross-link formation, it is likely that open or mismatched regions of DNA in cells may be particularly favorable for cross-link production. Herein, we investigated the effect of the local DNA sequence on the formation of interstrand cross-links, using 5-bromo-2'-deoxyuridine to generate radicals in a mismatched region of DNA. We investigated a total of 12 variations of bases in the mismatched region. The oligonucleotides were irradiated with gamma-rays, and interstrand cross-link formation was analyzed by denaturing gel electrophoresis. We found that the efficiency of cross-link formation was highly dependent on the nature of mismatched bases and, on the basis of electrophoretic mobility, observed several distinctive cross-link structures with specific DNA sequences. This study provides new insights into the reactivity of mismatched DNA and the mechanisms leading to interstrand cross-link formation. The potential application of 5-bromo-2'-deoxyuridine-induced interstrand cross-links to the field of DNA repair is discussed.
链间交联会阻碍转录和复制等关键细胞过程，因此被认为是最具毒性的DNA损伤类型之一。尽管目前有几项研究指出细胞DNA中存在γ射线诱导的交联，但对于其形成所需的特征却知之甚少。最近，我们报道了在5-溴-2'-脱氧尿苷取代的DNA中形成的链间交联对错配核苷酸具有特异性。鉴于链间交联形成的结构特异性，细胞中DNA的开放或错配区域可能特别有利于交联的产生。在此，我们使用5-溴-2'-脱氧尿苷在DNA的错配区域产生自由基，研究了局部DNA序列对链间交联形成的影响。我们总共研究了错配区域中12种碱基变体。用γ射线照射寡核苷酸，并通过变性凝胶电泳分析链间交联的形成。我们发现交联形成的效率高度依赖于错配碱基的性质，并根据电泳迁移率观察到几种具有特定DNA序列的独特交联结构。这项研究为错配DNA的反应性以及导致链间交联形成的机制提供了新的见解。还讨论了5-溴-2'-脱氧尿苷诱导的链间交联在DNA修复领域的潜在应用。
