Human Rad51 amino acid residues required for Rad52 binding

J Mol Biol. 1999 Aug 20;291(3):537-48. doi: 10.1006/jmbi.1999.2950.


The Rad51 protein, a homologue of the bacterial RecA protein, is an essential factor for both meiotic and mitotic recombination. The N-terminal domain of the human Rad51 protein (HsRad51) directly interacts with DNA. Based on a yeast two-hybrid analysis, it has been reported that the N-terminal region of the Saccharomyces cerevisiae Rad51 protein binds Rad52;S. cerevisiae Rad51 and Rad52 both activate the homologous pairing and strand exchange reactions. Here, we show that the HsRad51 N-terminal region, which corresponds to the Rad52-binding region of ScRad51, does not exhibit strong binding to the human Rad52 protein (HsRad52). To investigate its function, the C-terminal region of HsRad51 was randomly mutagenized. Although this region includes the two segments corresponding to the putative DNA-binding sites of RecA, all seven of the mutants did not decrease, but instead slightly increased, the DNA binding. In contrast, we found that some of these HsRad51 mutations significantly decreased the HsRad52 binding. Therefore, we conclude that these amino acid residues are required for the HsRad51.HsRad52 binding. HsRad52, as well as S. cerevisiae Rad52, promoted homologous pairing between ssDNA and dsDNA, and higher homologous pairing activity was observed in the presence of both HsRad51 and HsRad52 than with either HsRad51 or HsRad52 alone. The HsRad51 F259V mutation, which strongly impaired the HsRad52 binding, decreased the homologous pairing in the presence of both HsRad51 and HsRad52, without affecting the homologous pairing by HsRad51 alone. This result suggests the importance of the HsRad51.HsRad52 interaction in homologous pairing.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Binding Sites / genetics
  • DNA Primers / genetics
  • DNA, Single-Stranded / metabolism
  • DNA-Binding Proteins / chemistry*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Escherichia coli / genetics
  • Fungal Proteins / metabolism
  • Humans
  • In Vitro Techniques
  • Models, Molecular
  • Molecular Sequence Data
  • Mutagenesis
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Protein Binding
  • Protein Conformation
  • Rad51 Recombinase
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae Proteins
  • Sequence Homology, Amino Acid


  • DNA Primers
  • DNA, Single-Stranded
  • DNA-Binding Proteins
  • Fungal Proteins
  • Peptide Fragments
  • Recombinant Proteins
  • Saccharomyces cerevisiae Proteins
  • RAD51 protein, S cerevisiae
  • RAD51 protein, human
  • Rad51 Recombinase