Aylon Yael, Liefshitz Batia, Bitan-Banin Gili, Kupiec Martin
Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel.
Mol Cell Biol. 2003 Feb;23(4):1403-17. doi: 10.1128/MCB.23.4.1403-1417.2003.
Recombination plays a central role in the repair of broken chromosomes in all eukaryotes. We carried out a systematic study of mitotic recombination. Using several assays, we established the chronological sequence of events necessary to repair a single double-strand break. Once a chromosome is broken, yeast cells become immediately committed to recombinational repair. Recombination is completed within an hour and exhibits two kinetic gaps. By using this kinetic framework we also characterized the role played by several proteins in the recombinational process. In the absence of Rad52, the broken chromosome ends, both 5' and 3', are rapidly degraded. This is not due to the inability to recombine, since the 3' single-stranded DNA ends are stable in a strain lacking donor sequences. Rad57 is required for two consecutive strand exchange reactions. Surprisingly, we found that the Srs2 helicase also plays an early positive role in the recombination process.
在所有真核生物中，重组在修复断裂染色体过程中起着核心作用。我们对有丝分裂重组进行了系统研究。通过多种检测方法，我们确定了修复单个双链断裂所需事件的时间顺序。一旦染色体断裂，酵母细胞会立即进行重组修复。重组在一小时内完成，并呈现出两个动力学间隙。利用这个动力学框架，我们还表征了几种蛋白质在重组过程中所起的作用。在缺乏Rad52的情况下，断裂染色体的5'和3'末端都会迅速降解。这并非由于无法进行重组，因为在缺乏供体序列的菌株中，3'单链DNA末端是稳定的。Rad57参与连续两个链交换反应。令人惊讶的是，我们发现Srs2解旋酶在重组过程中也发挥早期积极作用。
