State Key Laboratory of Medicinal Chemical Biology, College of Pharmacy and Key Laboratory of Medical Data Analysis and Statistical Research of Tianjin, Nankai University, Tianjin 300353, China.
National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Nucleic Acids Res. 2021 Jul 21;49(13):7740-7752. doi: 10.1093/nar/gkab542.
The SLX1-SLX4 structure-specific endonuclease complex is involved in processing diverse DNA damage intermediates, including resolution of Holliday junctions, collapse of stalled replication forks and removal of DNA flaps. The nuclease subunit SLX1 is inactive on its own, but become activated upon binding to SLX4 via its conserved C-terminal domain (CCD). Yet, how the SLX1-SLX4 complex recognizes specific DNA structure and chooses cleavage sites remains unknown. Here we show, through a combination of structural, biochemical and computational analyses, that the SAP domain of SLX4 is critical for efficient and accurate processing of 5'-flap DNA. It binds the minor groove of DNA about one turn away from the flap junction, and the 5'-flap is implicated in binding the core domain of SLX1. This binding mode accounts for specific recognition of 5'-flap DNA and specification of cleavage site by the SLX1-SLX4 complex.
SLX1-SLX4 结构特异性内切酶复合物参与多种 DNA 损伤中间体的处理，包括解决 Holliday 连接、停滞复制叉的崩溃和去除 DNA 瓣。核酶亚基 SLX1 本身没有活性，但通过其保守的 C 末端结构域 (CCD) 与 SLX4 结合后被激活。然而，SLX1-SLX4 复合物如何识别特定的 DNA 结构并选择切割位点仍然未知。通过结构、生化和计算分析的结合，我们表明 SLX4 的 SAP 结构域对于 5'-flap DNA 的有效和准确处理至关重要。它结合 DNA 的小沟，距离 flap 连接约一个螺旋，并且 5'-flap 参与结合 SLX1 的核心结构域。这种结合模式解释了 SLX1-SLX4 复合物对 5'-flap DNA 的特异性识别和切割位点的指定。
