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Updated: Jan 1, 2026
Real-time Observation of the DNA Strand Exchange Reaction Mediated by Rad51
Published on: February 13, 2019
Design, synthesis and interaction of BRC4 analogous peptides with RAD51(241-260)
Jinlei Li1,2, Kui Lu3,4,5, Mingxiu Lv6
1College of Chemical, Zhengzhou University, Zhengzhou, 450001, China.
Abstract:
Breast cancer susceptibility gene 2 (BRCA2) is an important tumor suppressor, which is participated in repair of damaged DNA by its highly conserved BRC repeat motifs regulating RAD51 protein homologous recombination and thereby preventing cell carcinogenesis. In this study, the BRCA2(1524-1548)-RAD51(241-260) complex structure was obtained based on PDB bank data 1N0W, which provided the basis for site-specific mutation of BRCA2(1524-1548). The BRC4 and BRC4 analogous peptides were synthesized, and the interaction between BRC peptide and RAD51(241-260) was studied by fluorescence spectroscopy, circular dichroism spectroscopy and microscale thermophoresis (MST). The results of circular dichroism showed that the changes in secondary structures of RAD51(241-260) occurred after adding BRC4 analogous peptides, and the α-helix content increased significantly. Fluorescence spectral data demonstrated that the model of BRC peptide binding to RAD51(241-260) was static quenching, and the binding constants of BRC4, P1, P2, P4 with RAD51(241-260) were 1.647 × 10-4 L mol-1, 2.532 × 10-4 L mol-1, 3.161 × 10-4 L mol-1, 1.705 × 10-4 L mol-1, respectively. The results of MST indicated that P2 and RAD51(241-260) have better affinity for dissociation constant 44.286 μM. The strongest affinity between P2 and RAD51(241-260) indicated that the mutation of amino acid residue constituting BRC α-helix affects the structure and interaction of BRC peptide and RAD51(241-260).
Insights
Breast cancer susceptibility gene 2 (BRCA2) peptides, specifically BRC4 and analogs, interact with RAD51 protein to aid DNA repair. Peptide P2 showed the strongest affinity, suggesting mutations in the BRC alpha-helix impact BRCA2-RAD51 interactions.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Breast cancer susceptibility gene 2 (BRCA2) is a crucial tumor suppressor involved in DNA damage repair.
- BRCA2 utilizes conserved BRC repeat motifs to regulate RAD51 protein homologous recombination, preventing cell carcinogenesis.
Purpose of the Study:
- To investigate the interaction between BRCA2 peptides and RAD51 protein.
- To determine the structural and binding characteristics of specific BRCA2 BRC motifs with RAD51.
Main Methods:
- Obtained the BRCA2(1524-1548)-RAD51(241-260) complex structure from PDB ID 1N0W.
- Synthesized BRC4 and analogous peptides for interaction studies.
- Utilized fluorescence spectroscopy, circular dichroism (CD) spectroscopy, and microscale thermophoresis (MST) to analyze peptide-protein interactions.
Main Results:
- CD spectroscopy revealed that BRC4 analogous peptides induced changes in RAD51(241-260) secondary structure, increasing alpha-helix content.
- Fluorescence spectroscopy indicated a static quenching model for BRC peptide binding to RAD51(241-260).
- MST results showed the P2 peptide exhibited the strongest affinity for RAD51(241-260) with a dissociation constant of 44.286 μM.
Conclusions:
- The interaction between BRC peptides and RAD51(241-260) involves alterations in RAD51 secondary structure.
- Peptide P2 demonstrates the highest binding affinity to RAD51(241-260), highlighting the importance of specific amino acid residues within the BRC alpha-helix.
- These findings suggest that mutations affecting the BRC alpha-helix structure can influence the interaction between BRCA2 and RAD51, impacting DNA repair mechanisms.
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