DNA polymerase β uses its lyase domain in a processive search for DNA damage. Issue 7 (24th January 2017)

• Record Type: Journal Article
• Authors: Howard, Michael J.; Rodriguez, Yesenia; Wilson, Samuel H.
• Is Part Of: Nucleic acids research. Volume 45:Issue 7(2017)
• Page Start: 3822
• Page End: 3832
• Publication Date: 2017-01-24
• Subjects: Nucleic acids -- Periodicals; Molecular biology -- Periodicals; 572.805
• DOI: 10.1093/nar/gkx047
• Languages: English
• ISSNs: 0305-1048

Abstract

Abstract: DNA polymerase (Pol) β maintains genome fidelity by catalyzing DNA synthesis and removal of a reactive DNA repair intermediate during base excision repair (BER). Situated within the middle of the BER pathway, Pol β must efficiently locate its substrates before damage is exacerbated. The mechanisms of damage search and location by Pol β are largely unknown, but are critical for understanding the fundamental features of the BER pathway. We developed a processive search assay to determine if Pol β has evolved a mechanism for efficient DNA damage location. These assays revealed that Pol β scans DNA using a processive hopping mechanism and has a mean search footprint of ∼24 bp at predicted physiological ionic strength. Lysines within the lyase domain are required for processive searching, revealing a novel function for the lyase domain of Pol β. Application of our processive search assay into nucleosome core particles revealed that Pol β is not processive in the context of a nucleosome, and its single-turnover activity is reduced ∼500-fold, as compared to free DNA. These data suggest that the repair footprint of Pol β mainly resides within accessible regions of the genome and that these regions can be scanned for damage by Pol β.