Nucleic Acids Research Advance Access originally published online on August 20, 2008
Nucleic Acids Research 2008 36(17):5441-5450; doi:10.1093/nar/gkn516
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Nucleic Acids Research, 2008, Vol. 36, No. 17 5441-5450
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Molecular Biology |
Biochemical analysis of the N-terminal domain of human RAD54B
1Systems and Structural Biology Center, Yokohama Institute, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, 2Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, 3Graduate School of Advanced Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, 4Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai 980-8575 and 5Laboratory of Molecular Radiology, Center of Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
*To whom correspondence should be addressed. Tel: +81 3 5369 7315; Fax: +81 3 5367 2820; Email: kurumizaka{at}waseda.jp
Correspondence may also be addressed to Shigeyuki Yokoyama. Tel: +81 3 5841 4395; Fax: +81 3 5841 8057; Email: yokoyama{at}biochem.s.u-tokyo.ac.jp
Received April 25, 2008. Revised July 16, 2008. Accepted July 29, 2008.
The human RAD54B protein is a paralog of the RAD54 protein, which plays important roles in homologous recombination. RAD54B contains an N-terminal region outside the SWI2/SNF2 domain that shares less conservation with the corresponding region in RAD54. The biochemical roles of this region of RAD54B are not known, although the corresponding region in RAD54 is known to physically interact with RAD51. In the present study, we have biochemically characterized an N-terminal fragment of RAD54B, consisting of amino acid residues 26–225 (RAD54B26–225). This fragment formed a stable dimer in solution and bound to branched DNA structures. RAD54B26–225 also interacted with DMC1 in both the presence and absence of DNA. Ten DMC1 segments spanning the entire region of the DMC1 sequence were prepared, and two segments, containing amino acid residues 153–214 and 296–340, were found to directly bind to the N-terminal domain of RAD54B. A structural alignment of DMC1 with the Methanococcus voltae RadA protein, a homolog of DMC1 in the helical filament form, indicated that these RAD54B-binding sites are located near the ATP-binding site at the monomer–monomer interface in the DMC1 helical filament. Thus, RAD54B binding may affect the quaternary structure of DMC1. These observations suggest that the N-terminal domain of RAD54B plays multiple roles of in homologous recombination.