An atypical BRCT–BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex
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.
- Authors:
-
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Univ. of New Mexico, Albuquerque, NM (United States)
- Univ. of Montreal, QC (Canada)
- Univ. of Cincinnati, OH (United States)
- Washington Univ., St. Louis, MO (United States)
- Univ. of Texas, Houston, TX (United States)
- Publication Date:
- Research Org.:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC); National Institutes of Health (NIH); Cancer Prevention Research Institute of Texas (CPRIT); V Foundation; Natural Sciences and Engineering Research Council of Canada (NSERC)
- OSTI Identifier:
- 1766538
- Grant/Contract Number:
- AC02-05CH11231; R01 ES012512; R35 CA220430; P01 CA092584; P30 GM124169- 01 ALS-ENABLE; RP180813; V2018-25; RGPIN-2015-05776
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nucleic Acids Research
- Additional Journal Information:
- Journal Volume: 49; Journal Issue: 1; Journal ID: ISSN 0305-1048
- Publisher:
- Oxford University Press
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 59 BASIC BIOLOGICAL SCIENCES
Citation Formats
Hammel, Michal, Rashid, Ishtiaque, Sverzhinsky, Aleksandr, Pourfarjam, Yasin, Tsai, Miaw-Sheue, Ellenberger, Tom, Pascal, John M., Kim, In-Kwon, Tainer, John A., and Tomkinson, Alan E. An atypical BRCT–BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex. United States: N. p., 2020.
Web. doi:10.1093/nar/gkaa1188.
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. An atypical BRCT–BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex. United States. https://doi.org/10.1093/nar/gkaa1188
Hammel, Michal, Rashid, Ishtiaque, Sverzhinsky, Aleksandr, Pourfarjam, Yasin, Tsai, Miaw-Sheue, Ellenberger, Tom, Pascal, John M., Kim, In-Kwon, Tainer, John A., and Tomkinson, Alan E. Wed .
"An atypical BRCT–BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex". United States. https://doi.org/10.1093/nar/gkaa1188. https://www.osti.gov/servlets/purl/1766538.
@article{osti_1766538,
title = {An atypical BRCT–BRCT interaction with the XRCC1 scaffold protein compacts human DNA Ligase IIIα within a flexible DNA repair complex},
author = {Hammel, Michal and Rashid, Ishtiaque and Sverzhinsky, Aleksandr and Pourfarjam, Yasin and Tsai, Miaw-Sheue and Ellenberger, Tom and Pascal, John M. and Kim, In-Kwon and Tainer, John A. and Tomkinson, Alan E.},
abstractNote = {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.},
doi = {10.1093/nar/gkaa1188},
journal = {Nucleic Acids Research},
number = 1,
volume = 49,
place = {United States},
year = {Wed Dec 16 00:00:00 EST 2020},
month = {Wed Dec 16 00:00:00 EST 2020}
}
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