title: The N-terminal domain of the human Rad51 protein binds DNA: structure and a DNA binding surface as revealed by NMR.
abstract: Human Rad51 protein (HsRad51) is a homolog of Escherichia coli RecA protein, and functions in DNA repair and recombination. In higher eukaryotes, Rad51 protein is essential for cell viability. The N-terminal region of HsRad51 is highly conserved among eukaryotic Rad51 proteins but is absent from RecA, suggesting a Rad51-specific function for this region. Here, we have determined the structure of the N-terminal part of HsRad51 by NMR spectroscopy. The N-terminal region forms a compact domain consisting of five short helices, which shares structural similarity with a domain of endonuclease III, a DNA repair enzyme of E. coli. NMR experiments did not support the involvement of the N-terminal domain in HsRad51-HsBrca2 interaction or the self-association of HsRad51 as proposed by previous studies. However, NMR tiration experiments demonstrated a physical interaction of the domain with DNA, and allowed mapping of the DNA binding surface. Mutation analysis showed that the DNA binding surface is essential for double-stranded and single-stranded DNA binding of HsRad51. Our results suggest the presence of a DNA binding site on the outside surface of the HsRad51 filament and provide a possible explanation for the regulation of DNA binding by phosphorylation within the N-terminal domain.
authors.affiliation: Cellular & Molecular Biology Laboratory, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Aihara
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: H
authors.initials: H
authors.lastname: Kurumizaka
authors.forename: S
authors.initials: S
authors.lastname: Yokoyama
authors.forename: T
authors.initials: T
authors.lastname: Shibata
mesh_terms: D024682:BRCA2 Protein; D001665:Binding Sites; D017124:Conserved Sequence / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D043224:Deoxyribonuclease (Pyrimidine Dimer); D004706:Endodeoxyribonucleases / Q000737:chemistry; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017510:Protein Folding; D017433:Protein Structure, Secondary; D051135:Rad51 Recombinase; D011938:Rec A Recombinases / Q000737:chemistry; D055672:Static Electricity; D017186:Titrimetry; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D024682:BRCA2 Protein; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D009363:Neoplasm Proteins; D010446:Peptide Fragments; D014157:Transcription Factors; D004247:DNA; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D011938:Rec A Recombinases; D004706:Endodeoxyribonucleases; D043224:Deoxyribonuclease (Pyrimidine Dimer); C106403:NTH protein, E coli