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Biochemical analysis of the damage recognition process in nucleotide excision repair
Jin-Sam You1, Mu Wang, Suk-Hee Lee
1Department of Biochemistry and Molecular Biology, Indiana University Cancer Center, and Walther Oncology Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
Abstract:
XPA, XPC-hHR23B, RPA, and TFIIH all are the damage recognition proteins essential for the early stage of nucleotide excision repair. Nonetheless, it is not clear how these proteins work together at the damaged DNA site. To get insight into the molecular mechanism of damage recognition, we carried out a comprehensive analysis on the interaction between damage recognition proteins and their assembly on damaged DNA. XPC physically interacted with XPA, but failed to stabilize the XPA-damaged DNA complex. Instead, XPC-hHR23B was effectively displaced from the damaged DNA by the combined action of RPA and XPA. A mutant RPA lacking the XPA interaction domain failed to displace XPC-hHR23B from damaged DNA, suggesting that XPA and RPA cooperate with each other to destabilize the XPC-hHR23B-damaged DNA complex. Interestingly, the presence of hHR23B significantly increased RPA/XPA-mediated displacement of XPC from damaged DNA, suggesting that hHR23B may modulate the binding of XPC to damaged DNA. Together, our results suggest that damage recognition occurs in a multistep process such that XPC-hHR23B initiates damage recognition, which was replaced by combined action of XPA and RPA. XPA and RPA, once forming a complex at the damage site, would likely work with TFIIH, XPG, and ERCC1-XPF for dual incision.
Insights
Damage recognition in DNA repair involves a multistep process. XPC-hHR23B initiates recognition, followed by XPA and RPA cooperation to destabilize the complex for further repair steps.
Area of Science:
- Molecular Biology
- DNA Repair Mechanisms
- Protein Interactions
Background:
- Nucleotide excision repair (NER) is crucial for maintaining genomic stability.
- Key proteins like XPA, XPC-hHR23B, RPA, and TFIIH are vital for early DNA damage recognition.
- The precise assembly and interplay of these proteins at damaged DNA sites remain incompletely understood.
Purpose of the Study:
- To elucidate the molecular mechanism of DNA damage recognition during NER.
- To investigate the cooperative interactions among XPA, XPC-hHR23B, and RPA at damaged DNA.
- To understand the role of hHR23B in modulating XPC binding and displacement.
Main Methods:
- Comprehensive analysis of protein-DNA interactions.
- Investigating the assembly of damage recognition proteins on damaged DNA.
- Utilizing mutant RPA lacking the XPA interaction domain to assess protein displacement dynamics.
Main Results:
- XPC physically interacts with XPA but does not stabilize the XPA-damaged DNA complex.
- XPC-hHR23B is displaced from damaged DNA by the combined action of RPA and XPA.
- A mutant RPA lacking XPA interaction domain failed to displace XPC-hHR23B, indicating cooperative destabilization by XPA and RPA.
- hHR23B enhances the displacement of XPC by RPA/XPA, suggesting a modulatory role.
Conclusions:
- DNA damage recognition is a multistep process initiated by XPC-hHR23B.
- XPA and RPA cooperate to destabilize the initial XPC-hHR23B complex.
- This sequential replacement facilitates subsequent repair steps involving TFIIH, XPG, and ERCC1-XPF for dual incision.