Porebski Bartlomiej, Wild Sebastian, Kummer Sandra, Scaglione Sarah, Gaillard Pierre-Henri L, Gari Kerstin
Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland.
iScience. 2019 Nov 22;21:31-41. doi: 10.1016/j.isci.2019.10.010. Epub 2019 Oct 8.
During DNA replication stress, stalled replication forks need to be stabilized to prevent fork collapse and genome instability. The AAA + ATPase WRNIP1 (Werner Helicase Interacting Protein 1) has been implicated in the protection of stalled replication forks from nucleolytic degradation, but the underlying molecular mechanism has remained unclear. Here we show that WRNIP1 exerts its protective function downstream of fork reversal. Unexpectedly though, WRNIP1 is not part of the well-studied BRCA2-dependent branch of fork protection but seems to protect the junction point of reversed replication forks from SLX4-mediated endonucleolytic degradation, possibly by directly binding to reversed replication forks. This function is specific to the shorter, less abundant, and less conserved variant of WRNIP1. Overall, our data suggest that in the absence of BRCA2 and WRNIP1 different DNA substrates are generated at reversed forks but that nascent strand degradation in both cases depends on the activity of exonucleases and structure-specific endonucleases.
在DNA复制应激期间，停滞的复制叉需要被稳定以防止叉状结构崩溃和基因组不稳定。AAA+ATP酶WRNIP1（沃纳解旋酶相互作用蛋白1）与保护停滞的复制叉免受热解降解有关，但其潜在的分子机制仍不清楚。在这里，我们表明WRNIP1在叉状结构逆转的下游发挥其保护功能。然而，出乎意料的是，WRNIP1不是研究充分的BRCA2依赖性叉状结构保护分支的一部分，而是似乎通过直接结合逆转的复制叉来保护逆转的复制叉的连接点免受热解酶介导的核酸内切酶降解。该功能对WRNIP1较短、丰度较低且保守性较低的变体具有特异性。总体而言，我们的数据表明，在没有BRCA2和WRNIP1的情况下，在逆转的叉状结构处会产生不同的DNA底物，但在这两种情况下新生链的降解都取决于核酸外切酶和结构特异性核酸内切酶的活性。
