The Bloom's syndrome helicase unwinds G4 DNA.
BLM, the gene that is defective in Bloom's syndrome, encodes a protein homologous to RecQ subfamily helicases that functions as a 3'-5' DNA helicase in vitro. We now report that the BLM helicase can unwind G4 DNA. The BLM G4 DNA unwinding activity is ATP-dependent and requires a short 3' region of single-stranded DNA. Strikingly, G4 DNA is a preferred substrate of the BLM helicase, as measured both by efficiency of unwinding and by competition. These results suggest that G4 DNA may be a natural substrate of BLM in vivo and that the failure to unwind G4 DNA may cause the genomic instability and increased frequency of sister chromatid exchange characteristic of Bloom's syndrome.
Departments of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
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Sun
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Karow
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Hickson
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Maizels
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001816:Bloom Syndrome; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004261:DNA Replication; D006147:Guanine; D006801:Humans; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D053484:RecQ Helicases; D011995:Recombination, Genetic; D013379:Substrate Specificity
D006147:Guanine; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases