González-Barrera Sergio, Cortés-Ledesma Felipe, Wellinger Ralf E, Aguilera Andrés
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41012 Seville, Spain.
Mol Cell. 2003 Jun;11(6):1661-71. doi: 10.1016/s1097-2765(03)00183-7.
Equal sister chromatid exchange (SCE) has been thought to be an important mechanism of double-strand break (DSB) repair in eukaryotes, but this has never been proven due to the difficulty of distinguishing SCE products from parental molecules. To evaluate the biological relevance of equal SCE in DSB repair and to understand the underlying molecular mechanism, we developed recombination substrates for the analysis of DSB repair by SCE in yeast. In these substrates, most breaks are limited to one chromatid, allowing the intact sister chromatid to serve as the repair template; both equal and unequal SCE can be detected. We show that equal SCE is a major mechanism of DSB repair, is Rad51 dependent, and is stimulated by Rad59 and Mre11. Our work provides a physical analysis of mitotically occurring SCE in vivo and opens new perspectives for the study and understanding of DSB repair in eukaryotes.
姐妹染色单体等交换（SCE）被认为是真核生物中双链断裂（DSB）修复的重要机制，但由于难以将SCE产物与亲本分子区分开来，这一点从未得到证实。为了评估等SCE在DSB修复中的生物学相关性，并了解其潜在的分子机制，我们开发了重组底物，用于分析酵母中通过SCE进行的DSB修复。在这些底物中，大多数断裂仅限于一条染色单体，从而使完整的姐妹染色单体可作为修复模板；等SCE和不等SCE均可被检测到。我们表明，等SCE是DSB修复的主要机制，依赖于Rad51，并受到Rad59和Mre11的刺激。我们的工作为体内有丝分裂过程中发生的SCE提供了物理分析，并为真核生物中DSB修复的研究和理解开辟了新的视角。
