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Interference of papillomavirus E6 protein with single-strand break repair by interaction with XRCC1
Thomas Iftner1, Michaela Elbel, Betti Schopp
1Sektion Experimentelle Virologie, Universitätsklinikum Tuebingen, Elfriede-Aulhorn Strasse 6, D-72076 Tuebingen, Germany. tsiftner@med.uni-tuebingen.de
Abstract:
XRCC1 protein is required for the repair of DNA single-strand breaks and genetic stability, and is essential for viability in mammals. XRCC1 functions as a scaffold protein by interacting and modulating polypeptide components of the single-strand break repair machinery, including AP endonuclease-1, DNA ligase IIIalpha, poly (ADP-ribose) polymerase, DNA polymerase beta and human polynucleotide kinase. We show here that the E6 protein of human papillomavirus type 1, 8 and 16 directly binds XRCC1. When tested in CHO derived XRCC1 'knock out' EM9 cells, co-expression of human papillomavirus 16 E6 with human XRCC1 reduced the ability of the latter protein to correct the methyl methane sulfate sensitivity of XRCC1 mutant CHO cell line EM9. These data identify a novel link between small DNA tumour viruses and DNA repair pathways, and suggest a novel explanation for the development of genomic instability in tissue cells persistently infected with papillomaviruses.
Insights
Human papillomavirus E6 protein interacts with XRCC1, a key DNA repair protein. This interaction impairs DNA repair, potentially causing genomic instability in infected cells.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- X-ray Repair Cross Complementing 1 (XRCC1) is crucial for DNA single-strand break repair and maintaining genetic stability in mammals.
- XRCC1 acts as a scaffold, interacting with essential repair proteins like DNA ligase IIIalpha and poly (ADP-ribose) polymerase.
Purpose of the Study:
- To investigate the interaction between human papillomavirus (HPV) E6 proteins and the DNA repair protein XRCC1.
- To determine the functional consequences of this interaction on DNA repair capacity and genomic stability.
Main Methods:
- Co-immunoprecipitation assays to detect binding between HPV E6 and XRCC1.
- Functional assays using Chinese Hamster Ovary (CHO) derived XRCC1 'knock out' EM9 cells to assess methyl methanesulfonate sensitivity upon co-expression of HPV16 E6 and XRCC1.
Main Results:
- The E6 proteins from HPV types 1, 8, and 16 were shown to directly bind to XRCC1.
- Co-expression of HPV16 E6 with human XRCC1 in EM9 cells significantly reduced XRCC1's ability to correct methyl methanesulfonate sensitivity.
Conclusions:
- A novel functional link between small DNA tumor viruses and cellular DNA repair pathways has been identified.
- HPV E6 protein's interaction with XRCC1 offers a potential mechanism for the genomic instability observed in persistent papillomavirus infections.