title: Domain mapping of the Rad51 paralog protein complexes.
abstract: The five human Rad51 paralogs are suggested to play an important role in the maintenance of genome stability through their function in DNA double-strand break repair. These proteins have been found to form two distinct complexes in vivo, Rad51B-Rad51C-Rad51D-Xrcc2 (BCDX2) and Rad51C-Xrcc3 (CX3). Based on the recent Pyrococcus furiosus Rad51 structure, we have used homology modeling to design deletion mutants of the Rad51 paralogs. The models of the human Rad51B, Rad51C, Xrcc3 and murine Rad51D (mRad51D) proteins reveal distinct N-terminal and C-terminal domains connected by a linker region. Using yeast two-hybrid and co-immunoprecipitation techniques, we have demonstrated that a fragment of Rad51B containing amino acid residues 1-75 interacts with the C-terminus and linker of Rad51C, residues 79-376, and this region of Rad51C also interacts with mRad51D and Xrcc3. We have also determined that the N-terminal domain of mRad51D, residues 4-77, binds to Xrcc2 while the C-terminal domain of mRad51D, residues 77-328, binds Rad51C. By this, we have identified the binding domains of the BCDX2 and CX3 complexes to further characterize the interaction of these proteins and propose a scheme for the three-dimensional architecture of the BCDX2 and CX3 paralog complexes.
authors.affiliation: Biology and Biotechnology Research Program, Lawrence Livermore National Laboratory, 7000 East Avenue, L-448, Livermore, CA 94550, USA.
authors.forename: Kristi A
authors.initials: KA
authors.lastname: Miller
authors.forename: Dorota
authors.initials: D
authors.lastname: Sawicka
authors.forename: Daniel
authors.initials: D
authors.lastname: Barsky
authors.forename: Joanna S
authors.initials: JS
authors.lastname: Albala
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D019295:Computational Biology; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D046911:Macromolecular Substances; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D020027:Pyrococcus furiosus; D051135:Rad51 Recombinase; D016415:Sequence Alignment; D017384:Sequence Deletion / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; C413002:RAD51B protein, human; C448305:RAD51C protein, human; C112629:RAD51D protein, human; C491807:Rad51d protein, mouse; C113187:XRCC2 protein, human; C491866:Xrcc2 protein, mouse; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; C495154:Rad51 protein, mouse