Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Werner syndrome (WS) is a premature aging syndrome caused by mutations in the WS gene (WRN) and a deficiency in the function of the Werner protein (WRN). WRN is a multifunctional nuclear protein that catalyzes three DNA-dependent reactions: a 3'-5'-exonuclease, an ATPase, and a 3'-5'-helicase. Deficiency in WRN results in a cellular phenotype of genomic instability. The biochemical characteristics of WRN and the cellular phenotype of WRN mutants suggest that WRN plays an important role in DNA metabolic pathways such as recombination, transcription, replication, and repair. The catalytic activities of WRN have been extensively studied and are fairly well understood. However, much less is known about the domain-specific interactions between WRN and its DNA substrates. This study identifies and characterizes three distinct WRN DNA binding domains using recombinant truncated fragments of WRN and five DNA substrates (long forked duplex, blunt-ended duplex, single-stranded DNA, 5'-overhang duplex, and Holliday junction). Substrate-specific DNA binding activity was detected in three domains, one N-terminal and two different C-terminal WRN fragments (RecQ conserved domain and helicase RNase D conserved domain-containing domains). The substrate specificity of each DNA binding domain may indicate that each protein domain has a distinct biological function. The importance of these results is discussed with respect to proposed roles for WRN in distinct DNA metabolic pathways.
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PMID:Werner syndrome protein contains three structure-specific DNA binding domains. 1453 20

Werner syndrome (WS) is a premature aging disorder characterized by genomic instability and increased cancer risk (Martin, 1978). The WRN gene product defective in WS belongs to the RecQ family of DNA helicases (Yu et al., 1996). Mutations in RecQ family members BLM and RecQ4 result in two other disorders associated with elevated chromosomal instability and cancer, Bloom syndrome and Rothmund-Thomson syndrome, respectively (for review see Opresko et al., 2004a). RecQ helicase mutants display defects in DNA replication, recombination, and repair, suggesting a role for RecQ helicases in maintaining genomic integrity. The WRN gene encodes a 1,432 amino acid protein that has several catalytic activities (Brosh and Bohr, 2002) (Fig. 1). WRN is a DNA-dependent ATPase and utilizes the energy from ATP hydrolysis to unwind double-stranded DNA. WRN is also a 3' to 5' exonuclease, consistent with the presence of three conserved exonuclease motifs homologous to the exonuclease domain of Escherichia coli DNA polymerase I and RNase D. Most recently, WRN (Machwe et al., 2005) and other human RecQ helicases (Garcia et al., 2004; Machwe et al., 2005; Sharma et al., 2005) have been reported to possess an intrinsic single-strand annealing activity. In addition to its catalytic activities, WRN interacts with a number of proteins involved in various aspects of DNA metabolism. To understand the role of WRN in the maintenance of genome stability, a number of laboratories have undertaken a thorough characterization of its molecular and cellular functions. Here, we describe methods and approaches used for the functional and mechanistic analysis of WRN helicase or exonuclease activity. Protocols for measuring ATP hydrolysis, DNA binding, and catalytic unwinding or exonuclease activity of WRN protein are provided. Application of these procedures should enable the researcher to address fundamental questions regarding the biochemical properties of WRN or related helicases or nucleases, which would serve as a platform for further investigation of its molecular and cellular functions.
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PMID:Enzymatic mechanism of the WRN helicase/nuclease. 1679 95