Title: Stability and sub-cellular localization of DNA polymerase β is regulated by interactions with NQO1 and XRCC1 in response to oxidative stress.
Authors: Fang, Qingming; Andrews, Joel; Sharma, Nidhi; Wilk, Anna; Clark, Jennifer; Slyskova, Jana; Koczor, Christopher A; Lans, Hannes; Prakash, Aishwarya; Sobol, Robert W
Published In Nucleic Acids Res, (2019 07 09)
Abstract: Protein-protein interactions regulate many essential enzymatic processes in the cell. Somatic mutations outside of an enzyme active site can therefore impact cellular function by disruption of critical protein-protein interactions. In our investigation of the cellular impact of the T304I cancer mutation of DNA Polymerase β (Polβ), we find that mutation of this surface threonine residue impacts critical Polβ protein-protein interactions. We show that proteasome-mediated degradation of Polβ is regulated by both ubiquitin-dependent and ubiquitin-independent processes via unique protein-protein interactions. The ubiquitin-independent proteasome pathway regulates the stability of Polβ in the cytosol via interaction between Polβ and NAD(P)H quinone dehydrogenase 1 (NQO1) in an NADH-dependent manner. Conversely, the interaction of Polβ with the scaffold protein X-ray repair cross complementing 1 (XRCC1) plays a role in the localization of Polβ to the nuclear compartment and regulates the stability of Polβ via a ubiquitin-dependent pathway. Further, we find that oxidative stress promotes the dissociation of the Polβ/NQO1 complex, enhancing the interaction of Polβ with XRCC1. Our results reveal that somatic mutations such as T304I in Polβ impact critical protein-protein interactions, altering the stability and sub-cellular localization of Polβ and providing mechanistic insight into how key protein-protein interactions regulate cellular responses to stress.
PubMed ID: 31287140
MeSH Terms: Cell Line, Tumor; Chromatin/enzymology; Colonic Neoplasms/genetics; DNA Polymerase beta/chemistry; DNA Polymerase beta/genetics; DNA Polymerase beta/metabolism*; Enzyme Stability; Humans; Mutation; NAD(P)H Dehydrogenase (Quinone)/metabolism*; NAD/metabolism; Oxidative Stress*; Proteasome Endopeptidase Complex/metabolism; Ubiquitination; X-ray Repair Cross Complementing Protein 1/metabolism*