Nucleic Acids Research, 2002, Vol. 30, No. 17 3682-3691
© 2002 Oxford University Press
Drosophila melanogaster RECQ5/QE DNA helicase: stimulation by GTP binding
1 Cellular and Molecular Biology Laboratory and 2 Bioarchitect Research Group, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan, 3 CREST, JST (Japan Science and Technology), Wako, Saitama 351-0198, Japan and 4 Department of Molecular Biology, Faculty of Bioscience and Biotechnology, Saitama University, Saitamashi, Saitama 338-8570, Japan
*To whom correspondence should be addressed at: Cellular and Molecular Biology Laboratory, RIKEN (The Institute of Physical and Chemical Research), 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan. Tel: +81 48 467 9537; Fax: +81 48 462 4671; Email: tshibata{at}postman.riken.go.jp
The Drosophila melanogaster RECQ5/QE gene encodes a member of the DNA helicase family comprising the Escherichia coli RecQ protein and products of the human Bloom’s, Werner’s, and Rothmund-Thomson syndrome genes. The full-length product of RECQ5/QE was expressed in the baculovirus system and was purified. Gel filtration experiments indicated that RECQ5/QE was present in an oligomeric state. The RECQ5/QE protein hydrolyzed ATP and even more actively GTP in the presence of single-stranded DNA. ATP drove the DNA helicase activity of RECQ5/QE, whereas GTP had little effect. GTP exhibited a stimulatory effect on DNA unwinding when it was used together with ATP. This effect was more apparent with non-hydrolyzable GTP analogs, such as GTP
S and GMPPNP. These results indicate that GTP binding to RECQ5/QE triggers its DNA helicase activity. GTP binding increased the rate of strand separation without affecting the S0.5 (Km) values for the substrates during the DNA helicase reaction. The data collectively suggest that the RECQ5/QE protein is activated upon GTP binding through the ATP-binding site.