Human RECQ5beta, a protein with DNA helicase and strand-annealing activities in a single polypeptide.
Proteins belonging to the highly conserved RecQ helicase family are essential for the maintenance of genomic stability. Here, we describe the biochemical properties of the human RECQ5beta protein. Like BLM and WRN, RECQ5beta is an ATP-dependent 3'-5' DNA helicase that can promote migration of Holliday junctions. However, RECQ5beta required the single-stranded DNA-binding protein RPA in order to mediate the efficient unwinding of oligonucleotide-based substrates. Surprisingly, we found that RECQ5beta possesses an intrinsic DNA strand-annealing activity that is inhibited by RPA. Analysis of deletion variants of RECQ5beta revealed that the DNA helicase activity resides in the conserved N-terminal portion of the protein, whereas strand annealing is mediated by the unique C-terminal domain. Moreover, the strand-annealing activity of RECQ5beta was strongly inhibited by ATPgammaS, a poorly hydrolyzable analog of ATP. This effect was alleviated by mutations in the ATP-binding motif of RECQ5beta, indicating that the ATP-bound form of the protein cannot promote strand annealing. This is the first demonstration of a DNA helicase with an intrinsic DNA strand-annealing function residing in a separate domain.
Garcia
Patrick L
PL
Institute of Molecular Cancer Research, University of Zürich, Zürich, Switzerland.
Liu
Yilun
Y
Jiricny
Josef
J
West
Stephen C
SC
Janscak
Pavel
P
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D004265:DNA Helicases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D045566:DNA, Cruciform / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005090:Exodeoxyribonucleases; D017353:Gene Deletion; D014644:Genetic Variation; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D010455:Peptides / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D053484:RecQ Helicases; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification / Q000378:metabolism; D051716:Replication Protein A; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D000071657:Werner Syndrome Helicase
D045566:DNA, Cruciform; D004268:DNA-Binding Proteins; D007527:Isoenzymes; D010455:Peptides; D011506:Proteins; C506732:RECQL5 protein, human; C497167:RPA1 protein, human; D011993:Recombinant Fusion Proteins; D051716:Replication Protein A; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate; D005090:Exodeoxyribonucleases; D000251:Adenosine Triphosphatases; C097151:Bloom syndrome protein; D004265:DNA Helicases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase