Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

National Institute of Environmental Health Sciences

Use this QR code to view the newest version of this document
Use this QR code to view the newest version of this document

Your Environment. Your Health.

Publication Detail

Title: An atypical BRCT-BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex.

Authors: Hammel, Michal; Rashid, Ishtiaque; Sverzhinsky, Aleksandr; Pourfarjam, Yasin; Tsai, Miaw-Sheue; Ellenberger, Tom; Pascal, John M; Kim, In-Kwon; Tainer, John A; Tomkinson, Alan E

Published In Nucleic Acids Res, (2021 01 11)

Abstract: The XRCC1-DNA ligase IIIα complex (XL) is critical for DNA single-strand break repair, a key target for PARP inhibitors in cancer cells deficient in homologous recombination. Here, we combined biophysical approaches to gain insights into the shape and conformational flexibility of the XL as well as XRCC1 and DNA ligase IIIα (LigIIIα) alone. Structurally-guided mutational analyses based on the crystal structure of the human BRCT-BRCT heterodimer identified the network of salt bridges that together with the N-terminal extension of the XRCC1 C-terminal BRCT domain constitute the XL molecular interface. Coupling size exclusion chromatography with small angle X-ray scattering and multiangle light scattering (SEC-SAXS-MALS), we determined that the XL is more compact than either XRCC1 or LigIIIα, both of which form transient homodimers and are highly disordered. The reduced disorder and flexibility allowed us to build models of XL particles visualized by negative stain electron microscopy that predict close spatial organization between the LigIIIα catalytic core and both BRCT domains of XRCC1. Together our results identify an atypical BRCT-BRCT interaction as the stable nucleating core of the XL that links the flexible nick sensing and catalytic domains of LigIIIα to other protein partners of the flexible XRCC1 scaffold.

PubMed ID: 33330937 Exiting the NIEHS site

MeSH Terms: Chromatography, Gel; Crystallography, X-Ray; DNA Ligase ATP/chemistry; DNA Ligase ATP/metabolism*; DNA Repair*; Dimerization; Humans; Microscopy, Electron; Models, Molecular; Multiprotein Complexes; Mutation; Mutation, Missense; Negative Staining; Point Mutation; Protein Conformation; Protein Domains; Protein Interaction Mapping; Recombinant Proteins/metabolism; Scattering, Small Angle; X-ray Repair Cross Complementing Protein 1/chemistry; X-ray Repair Cross Complementing Protein 1/genetics; X-ray Repair Cross Complementing Protein 1/metabolism*

Back
to Top