The Bloom's Syndrome Helicase Unwinds G4 DNA

Hui Sun, Julia K. Karow, Ian D. Hickson, Nancy Maizels
1998 Journal of Biological Chemistry  
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
more » ... 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.
doi:10.1074/jbc.273.42.27587 pmid:9765292 fatcat:gnp2daszcnbbxnkcpl73wzdnja