Sedletska Yuliya, Culard Françoise, Midoux Patrick, Malinge Jean-Marc
Centre de Biophysique Moléculaire, CNRS UPR 4301, affiliated to the University of Orléans and INSERM, rue Charles Sadron, 45071 Orléans Cedex 02, France.
Biopolymers. 2013 Sep;99(9):636-47. doi: 10.1002/bip.22232.
The DNA mismatch repair (MMR) system participates in cis-diamminedichloroplatinum (II) (cisplatin) cytotoxicity through signaling of cisplatin DNA lesions by yet unknown molecular mechanisms. It is thus of great interest to determine whether specialized function of MMR proteins could be associated with cisplatin DNA damage. The major cisplatin 1,2-d(GpG) intrastrand crosslink and compound lesions arising from misincorporation of a mispaired base opposite either platinated guanine of the 1,2-d(GpG) adduct are thought to be critical lesions for MMR signaling. Previously, we have shown that cisplatin compound lesion with a mispaired thymine opposite the 3' platinated guanine triggers new Escherichia coli MutS ATP-dependent biochemical activities distinguishable from those encountered with DNA mismatch consistent with a role of this lesion in MMR-dependent signaling mechanism. In this report, we show that the major cisplatin 1,2-d(GpG) intrastrand crosslink does not confer novel MutS postrecognition biochemical activity as studied by surface plasmon resonance spectroscopy. A fast rate of MutS ATP-dependent dissociation prevents MutL recruitment to the major cisplatin lesion in contrast to cisplatin compound lesion which authorized MutS-dependent recruitment of MutL with a dynamic of ternary complex formation distinguishable from that encountered with DNA mismatch substrate. We conclude that the mode of cisplatin DNA damage recognition by MutS and the nature of MMR post-recognition events are lesion-dependent and suggest that MMR signaling through the major cisplatin lesion is unlikely to occur.
DNA错配修复（MMR）系统通过尚未明确的分子机制对顺铂DNA损伤进行信号传导，从而参与顺二氯二氨铂（II）（顺铂）的细胞毒性作用。因此，确定MMR蛋白的特殊功能是否与顺铂DNA损伤相关具有重要意义。顺铂主要的1,2 - d（GpG）链内交联以及由与1,2 - d（GpG）加合物的铂化鸟嘌呤相对的错配碱基错掺入而产生的复合损伤，被认为是MMR信号传导的关键损伤。此前，我们已经表明，与3'铂化鸟嘌呤相对的错配胸腺嘧啶形成的顺铂复合损伤会触发新的大肠杆菌MutS ATP依赖性生化活性，这与DNA错配所涉及的活性不同，表明该损伤在MMR依赖性信号传导机制中发挥作用。在本报告中，我们通过表面等离子体共振光谱研究表明，主要的顺铂1,2 - d（GpG）链内交联不会赋予MutS识别后新的生化活性。与顺铂复合损伤不同，MutS ATP依赖性快速解离阻止了MutL募集到主要的顺铂损伤处，顺铂复合损伤允许MutS依赖性募集MutL，其三元复合物形成动态与DNA错配底物不同。我们得出结论，MutS对顺铂DNA损伤的识别模式以及MMR识别后事件的性质取决于损伤类型，并表明通过主要顺铂损伤进行MMR信号传导不太可能发生。
