The HRDC domain of BLM is required for the dissolution of double Holliday junctions.
Bloom's syndrome is a hereditary cancer-predisposition disorder resulting from mutations in the BLM gene. In humans, BLM encodes one of five members of the RecQ helicase family. One function of BLM is to act in concert with topoisomerase IIIalpha (TOPO IIIalpha) to resolve recombination intermediates containing double Holliday junctions by a process called double Holliday junction dissolution, herein termed dissolution. Here, we show that dissolution is highly specific for BLM among human RecQ helicases and critically depends upon a functional HRDC domain in BLM. We show that the HRDC domain confers DNA structure specificity, and is required for the efficient binding to and unwinding of double Holliday junctions, but not for the unwinding of a simple partial duplex substrate. Furthermore, we show that lysine-1270 of BLM, which resides in the HRDC domain and is predicted to play a role in mediating interactions with DNA, is required for efficient dissolution.
Wu
Leonard
L
Cancer Research UK Laboratories, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford, UK.
Chan
Kok Lung
KL
Ralf
Christine
C
Bernstein
Douglas A
DA
Garcia
Patrick L
PL
Bohr
Vilhelm A
VA
Vindigni
Alessandro
A
Janscak
Pavel
P
Keck
James L
JL
Hickson
Ian D
ID
D000251:Adenosine Triphosphatases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D001816:Bloom Syndrome / Q000235:genetics / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics* / Q000378:metabolism; D045566:DNA, Cruciform / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D053484:RecQ Helicases; D020539:Sequence Analysis, Protein
D045566:DNA, Cruciform; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; D008239:Lysine