Biochemical Characterization of the WRN-1 RecQ Helicase of Caenorhabditis elegans

• Published in: Biochemistry (Easton) 2008-07, Vol.47 (28), p.7583-7593
• Main Authors: Hyun, Moonjung, Bohr, Vilhelm A, Ahn, Byungchan
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphatases - metabolism; Animals; Caenorhabditis elegans - enzymology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - isolation & purification; Caenorhabditis elegans Proteins - metabolism; Conserved Sequence; DNA - genetics; DNA Damage; DNA Helicases - genetics; DNA Helicases - isolation & purification; DNA Helicases - metabolism; DNA Repair; DNA Replication; Genotype; Recombinant Proteins - isolation & purification; Recombinant Proteins - metabolism; Substrate Specificity
• ISSN: 0006-2960; 1520-4995
• DOI: 10.1021/bi800197m

The highly conserved RecQ helicases are essential for the maintenance of genomic stability. Werner syndrome protein, WRN, is one of five human RecQ helicase homologues, and a deficiency of the protein causes a hereditary premature aging disorder that is characterized by genomic instability. A WRN orthologue, wrn-1 lacking the exonuclease domain, has been identified in the nematode Caenorhabditis elegans. wrn-1(RNAi) in C. elegans has a shortened life span, increased sensitivity to DNA damage, and accelerated aging phenotypes. However, little is known about its enzymatic activity. We purified the recombinant C. elegans WRN-1 protein (CeWRN-1) and then investigated its substrate specificity in vitro to improve our understanding of its function in vivo. We found that CeWRN-1 is an ATP-dependent 3′−5′ helicase capable of unwinding a variety of DNA structures such as forked duplexes, Holliday junctions, bubble substrates, D-loops, and flap duplexes, and 3′-tailed duplex substrates. Distinctly, CeWRN-1 is able to unwind a long forked duplex compared to human WRN. Furthermore, CeWRN-1 helicase activity on a long DNA duplex is stimulated by C. elegans replication protein A (CeRPA) that is shown to interact with CeWRN-1 by a dot blot. The ability of CeWRN-1 to unwind these DNA structures may improve the access for DNA repair and replication proteins that are important for preventing the accumulation of abnormal structures, contributing to genomic stability.