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Human RECQ5β, a protein with DNA helicase and strand‐annealing activities in a single polypeptide
Author(s) -
Garcia Patrick L,
Liu Yilun,
Jiricny Josef,
West Stephen C,
Janscak Pavel
Publication year - 2004
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600301
Subject(s) - biology , helicase , dna , rna helicase a , genetics , microbiology and biotechnology , biochemistry , rna , gene
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 RECQ5β protein. Like BLM and WRN, RECQ5β is an ATP‐dependent 3′–5′ DNA helicase that can promote migration of Holliday junctions. However, RECQ5β required the single‐stranded DNA‐binding protein RPA in order to mediate the efficient unwinding of oligonucleotide‐based substrates. Surprisingly, we found that RECQ5β possesses an intrinsic DNA strand‐annealing activity that is inhibited by RPA. Analysis of deletion variants of RECQ5β 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 RECQ5β was strongly inhibited by ATPγS, a poorly hydrolyzable analog of ATP. This effect was alleviated by mutations in the ATP‐binding motif of RECQ5β, 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.