Molecular interplay in eukaryotic nucleotide excision repair
Final Report Abstract
This project has enabled us to foster our knowledge on the intricate interaction network of the TFIIH complex, with a special focus on XPD helicase regulation. This was of particular importance since switching XPD activity on and off is vital for the different tasks of TFIIH during NER and transcription initiation. We could show that XPD’s activity is dominated by inhibition of MAT1 in the context of TFIIH via shielding of residues that are functionally important for helicase activity located in the Arch domain of XPD. This was an unexpected observation and redefined the functionality of XPD’s Arch domain. The importance of the Arch domain was further emphasized when our analysis revealed that it interacts with XPG and in addition might contribute to the stabilization of complexes during the incision process. We also showed that the interaction between the TFIIH subunits p34 and p44 is vital for TFIIH function and identified a previously undetected p34/p44 interface that is mediated by the C4 domain of p34. The project allowed us to gain significant insights into the damage verification process of which XPD is an integral part. We were able to demonstrate that XPD employs a different lesion recognition strategy as compared to the prokaryotic protein UvrB. In contrast to UvrB, XPD is able to recognize damages on both DNA strands. This observation requires further investigation and needs be put into the context of the complete TFIIH and NER machinery and to investigate whether our results on the importance of the Arch domain could influence this behavior. In the context of damage verification we could further identify the TFIIH subunits p44 and p62 as major XPD regulators that also modulate XPD’s behavior towards damaged DNA. This finding went along with the identification of the highly unexpected, damaged DNA binding properties of the p44/p62 subcomplex. Overall, our data significantly enhanced the knowledge on XPD regulation within the TFIIH complex. Our results have major implications for the damage verification strategies that are employed by TFIIH during eukaryotic NER and have provided a basis for further experiments to elucidate how damage verification via XPD is regulated and achieved.
Publications
- (2016). "Conservation and Divergence in Nucleotide Excision Repair Lesion Recognition." J Biol Chem 291(36): 18932-18946
Wirth, N., J. Gross, H. M. Roth, C. N. Buechner, C. Kisker and I. Tessmer
(See online at https://doi.org/10.1074/jbc.M116.739425) - (2017). "The intricate network between the p34 and p44 subunits is central to the activity of the transcription/DNA repair factor TFIIH." Nucleic Acids Res 45(18): 10872-10883
Radu, L., E. Schoenwetter, C. Braun, J. Marcoux, W. Koelmel, D. R. Schmitt, J. Kuper, S. Cianferani, J. M. Egly, A. Poterszman and C. Kisker
(See online at https://doi.org/10.1093/nar/gkx743) - (2020). "In TFIIH the Arch domain of XPD is mechanistically essential for transcription and DNA repair." Nat Commun 11(1): 1667
Peissert, S., F. Sauer, D. B. Grabarczyk, C. Braun, G. Sander, A. Poterszman, J. M. Egly, J. Kuper and C. Kisker
(See online at https://doi.org/10.1038/s41467-020-15241-9) - (2020). "The TFIIH subunits p44/p62 act as a damage sensor during nucleotide excision repair." Nucleic Acids Res 48(22): 12689-12696
Barnett, J. T., J. Kuper, W. Koelmel, C. Kisker and N. M. Kad
(See online at https://doi.org/10.1093/nar/gkaa973)
