A structure-specific nucleic acid-binding domain conserved among DNA repair proteins

Area of Science:

• Molecular Biology
• Genetics
• Structural Biology

Background:

• SMARCAL1 is essential for genome integrity and linked to Schimke immuno-osseous dysplasia (SIOD).
• SMARCAL1-deficient cells exhibit replication fork collapse and genomic instability.
• The function of SMARCAL1's HARP domain in DNA repair remains unclear.

Purpose of the Study:

• To elucidate the structure and function of the SMARCAL1 HARP domain.
• To understand the role of the HARP domain in DNA translocase mechanisms.
• To investigate the HARP domain's contribution to replication fork stability.

Main Methods:

• Crystal structure determination of the SMARCAL1 HARP domain.
• Small-angle X-ray scattering (SAXS) to study domain conformation and assembly.
• Functional assays using T4 phage UvsW protein and mutated SMARCAL1 catalytic domain.

Main Results:

• The crystal structure of the SMARCAL1 HARP domain was determined.
• The HARP domain is structurally homologous to DNA recognition domains in other repair proteins.
• The HARP domain is essential for DNA binding and fork regression activity of SMARCAL1.

Conclusions:

• The SMARCAL1 HARP domain acts as a conserved substrate recognition module in DNA repair enzymes.
• This domain couples ATP hydrolysis to DNA structure remodeling, ensuring replication fork stability.
• The findings provide insights into genome integrity maintenance and SIOD pathogenesis.