Identification and characterization of SMARCAL1 protein complexes.

B├ętous R, Glick GG, Zhao R, Cortez D
PLoS One. 2013 8 (5): e63149

PMID: 23671665 · PMCID: PMC3650004 · DOI:10.1371/journal.pone.0063149

SMARCAL1 is an ATPase in the SNF2 family that functions at damaged replication forks to promote their stability and restart. It acts by translocating on DNA to catalyze DNA strand annealing, branch migration, and fork regression. Many SNF2 enzymes work as motor subunits of large protein complexes. To determine if SMARCAL1 is also a member of a protein complex and to further understand how it functions in the replication stress response, we used a proteomics approach to identify interacting proteins. In addition to the previously characterized interaction with replication protein A (RPA), we found that SMARCAL1 forms complexes with several additional proteins including DNA-PKcs and the WRN helicase. SMARCAL1 and WRN co-localize at stalled replication forks independently of one another. The SMARCAL1 interaction with WRN is indirect and is mediated by RPA acting as a scaffold. SMARCAL1 and WRN act independently to prevent MUS81 cleavage of the stalled fork. Biochemical experiments indicate that both catalyze fork regression with SMARCAL1 acting more efficiently and independently of WRN. These data suggest that RPA brings a complex of SMARCAL1 and WRN to stalled forks, but that they may act in different pathways to promote fork repair and restart.

MeSH Terms (22)

Cell Line, Tumor DNA DNA-Binding Proteins DNA Breaks, Double-Stranded DNA Helicases DNA Repair DNA Replication Endonucleases Exodeoxyribonucleases HEK293 Cells HeLa Cells Humans Immunoblotting Immunoprecipitation Mass Spectrometry Nucleic Acid Conformation Protein Binding Proteomics RecQ Helicases Replication Protein A S Phase Werner Syndrome Helicase

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