RECQ5 Helicase Cooperates with MUS81 Endonuclease in Processing Stalled Replication Forks at Common Fragile Sites...

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• The MUS81-EME1 endonuclease resolves replication stress by cleaving late replication intermediates at common fragile sites (CFSs).
• Faithful chromosome segregation relies on DNA repair synthesis at CFSs during early mitosis.

Purpose of the Study:

• To investigate the role of RECQ5 DNA helicase in MUS81-EME1-mediated DNA repair at CFSs.
• To elucidate the mechanism by which RECQ5 promotes DNA repair synthesis and ensures chromosome stability.

Main Methods:

• Studied RECQ5's interaction with MUS81 and its dependence on CDK1 phosphorylation.
• Assessed the impact of RECQ5 depletion or mutation on RAD51 binding and CFS expression.
• Performed biochemical assays to analyze RECQ5's effect on MUS81-EME1 endonuclease activity in the presence of RAD51.

Main Results:

• RECQ5 associates with CFSs in early mitosis via MUS81 and promotes MUS81-dependent DNA synthesis.
• RECQ5 depletion or inactivation leads to increased RAD51 binding at CFSs, impairing their expression and causing defective chromosome segregation.
• RECQ5 disrupts RAD51 filaments, relieving RAD51-mediated inhibition of MUS81-EME1 cleavage of 3'-flap DNA.

Conclusions:

• RECQ5 facilitates MUS81-EME1 cleavage of stalled replication forks at CFSs by removing inhibitory RAD51 filaments.
• RECQ5 plays a crucial role in maintaining genome stability by promoting DNA repair and ensuring accurate chromosome segregation.
• CDK1-mediated phosphorylation of RECQ5 is essential for its function in DNA repair at CFSs.