The helicase and ATPase activities of RECQL4 are compromised by mutations reported in three human patients

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• RECQL4 is a member of the human RecQ helicase family.
• RECQL4 is associated with syndromes characterized by premature aging, developmental issues, and cancer predisposition.

Purpose of the Study:

• To investigate the biochemical and cellular consequences of patient-derived RECQL4 mutations.
• To determine the impact of specific RECQL4 variants on its DNA binding, unwinding, ATPase, and DNA damage response activities.

Main Methods:

• Purification of three RECQL4 protein variants with known patient mutations.
• In vitro analysis of DNA binding, DNA unwinding, ATP hydrolysis, and DNA annealing activities.
• Assessment of protein stability and recruitment to laser-induced DNA damage sites.

Main Results:

• One mutant was helicase-dead with minimal ATPase activity and potential structural instability.
• The other two mutants exhibited significantly reduced helicase and ATPase functions.
• DNA binding, annealing, and recruitment to DNA damage sites were largely unaffected in all mutants.

Conclusions:

• RECQL4 mutations consistently lead to functional deficiencies, particularly in helicase and ATPase activities.
• Findings support a crucial helicase-dependent cellular role for RECQL4 beyond its N-terminus-dependent replication initiation function.
• These deficiencies likely contribute to the pathogenesis of RECQL4-linked diseases.