Coordination of Structure-Specific Nucleases by Human SLX4/BTBD12 Is Required for DNA Repair

Abstract

Budding yeast Slx4 interacts with the structure-specific endonuclease Slx1 to ensure completion of ribosomal DNA replication. Slx4 also interacts with the Rad1-Rad10 endonuclease to control cleavage of 3' flaps during repair of double-strand breaks (DSBs). Here we describe the identification of human SLX4, a scaffold for DNA repair nucleases XPF-ERCC1, MUS81-EME1, and SLX1. SLX4 immunoprecipitates show SLX1-dependent nuclease activity toward Holliday junctions and MUS81-dependent activity toward other branched DNA structures. Furthermore, SLX4 enhances the nuclease activity of SLX1, MUS81, and XPF. Consistent with a role in processing recombination intermediates, cells depleted of SLX4 are hypersensitive to genotoxins that cause DSBs and show defects in the resolution of interstrand crosslink-induced DSBs. Depletion of SLX4 causes a decrease in DSB-induced homologous recombination. These data show that SLX4 is a regulator of structure-specific nucleases and that SLX4 and SLX1 are important regulators of genome stability in human cells.

Involvement of SLX4 in interstrand cross-link repair is regulated by the Fanconi anemia pathway

“…The present work extends previous studies with the yeast and human SLX4 homologs (21,22,24,26) and confirms that SLX4 plays a key role as an interacting platform for enzymes involved in the processing of HR intermediates and also links SLX4 to the repair of ICLs, a process coordinated by the FA pathway.…”

“…The latter polypeptide also interacts with SLX1 in both yeast (23,24) and mammalian cells (21,22,25,26), and the resulting complex displays 5′-flap endonuclease and Holliday junction resolvase activities. Based on this evidence, SLX4 has been assigned the role of a docking platform for structure-specific endonucleases, and its pivotal role in regulating their activities is underscored by the finding that SLX4 down-regulation sensitizes human cells to a wide variety of DNA-damaging agents (21,22,25,26). However, although SLX4 also has been implicated in ICL repair, its role in this process, as well as its possible link to the FA pathway, remain to be elucidated.…”

“…The structure-specific endonucleases XPF-ERCC1 and MUS81-EME1, which are implicated in ICL repair and in the resolution of homologous recombination (HR) intermediates (13)(14)(15)(16)(17)(18)(19)(20)(21)(22), interact with SLX4. The latter polypeptide also interacts with SLX1 in both yeast (23,24) and mammalian cells (21,22,25,26), and the resulting complex displays 5′-flap endonuclease and Holliday junction resolvase activities.…”

Fanconi anemia: a model disease for studies on human genetics and advanced therapeutics

“…BTBD12/SLX4 provides a platform for several endonucleases involved in ICL repair, including ERCC4-ERCC1, MUS81-EME1, and SLX1 that dock to cleave DNA flaps, replication forks, and Holliday junctions [46][47][48]. SLX4 is mutated in patients with bona fide FA (FANCP) [2,20].…”

HIV-1 Vpr degrades the HLTF DNA translocase in T cells and macrophages

“…More recently, Vpr has been shown to activate the SLX4 complex (SLX4com) with the help of DCAF1 (21,30). SLX4com associates with several endonucleases, including Mus81, to coordinate the repair of specific replication-born double strand breaks (DSBs) and collapsed replication forks (31)(32)(33). It has been proposed that Vpr triggers replication stress and G2 arrest through inappropriate activation of SLX4com (30).…”