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Allosteric inhibition of human exonuclease1 (hExo1) through a novel extended β-sheet conformation
DOI:
10.1016/j.bbagen.2020.129730
Authors:
Aminu Argungu
Umar
(University of Nottingham; Kebbi State University of Science and Technology)
,
Susan
Liddell
(University of Nottingham)
,
Rohanah
Hussain
(Diamond Light Source)
,
Giuliano
Siligardi
(Diamond Light Source)
,
Gemma
Harris
(Research Complex at Harwell)
,
Stephen
Carr
(Research Complex at Harwell)
,
Karishma
Asiani
(University of Nottingham)
,
Darren M.
Gowers
(University of Portsmouth)
,
Mark
Odell
(University of Westminster)
,
David J.
Scott
(University of Nottingham; Research Complex at Harwell; ISIS Spallation Neutron and Muon Source)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Biochimica Et Biophysica Acta (bba) - General Subjects
, VOL 1864
State:
Published (Approved)
Published:
December 2020
Diamond Proposal Number(s):
15313
,
14658
,
14430
Abstract: Background: Human Exonuclease1 (hExo1) participates in the resection of DNA double-strand breaks by generating long 3′-single-stranded DNA overhangs, critical for homology-based DNA repair and activation of the ATR-dependent checkpoint. The C-terminal region is essential for modulating the activity of hExo1, containing numerous sites of post-translational modification and binding sites for partner proteins. Methods: Analytical Ultracentrifugation (AUC), Dynamic Light Scattering (DLS), Circular Dichroism (CD) spectroscopy and enzymatic assays. Results: AUC and DLS indicates the C-terminal region has a highly extended structure while CD suggest a tendency to adopt a novel left-handed β-sheet structure, together implying the C-terminus may exhibit a transient fluctuating structure that could play a role in binding partner proteins known to regulate the activity of hExo1. Interaction with 14–3-3 protein has a cooperative inhibitory effect upon DNA resection activity, which indicates an allosteric transition occurs upon binding partner proteins. Conclusions: This study has uncovered that hExo1 consist of a folded N-terminal nuclease domain and a highly extended C-terminal region which is known to interact with partner proteins that regulates the activity of hExo1. A positively cooperative mechanism of binding allows for stringent control of hExo1 activity. Such a transition would coordinate the control of hExo1 by hExo1 regulators and hence allow careful coordination of the process of DNA end resection.
Journal Keywords: Intrinsic disorder; Circular dichroism; Allostery; Exonuclease; Enzyme assay
Subject Areas:
Biology and Bio-materials,
Chemistry
Instruments:
B23-Circular Dichroism