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Metal Exchange in the Interprotein Zn II ‐Binding Site of the Rad50 Hook Domain: Structural Insights into Cd II ‐Induced DNA‐Repair Inhibition
Author(s) -
Padjasek Michał,
Maciejczyk Maciej,
Nowakowski Michał,
Kerber Olga,
Pyrka Maciej,
Koźmiński Wiktor,
Krężel Artur
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904942
Subject(s) - chemistry , zinc finger , peptide , biophysics , zinc , genotoxicity , dna , crystallography , biochemistry , transcription factor , biology , organic chemistry , toxicity , gene
Cd II is a major genotoxic agent that readily displaces Zn II in a multitude of zinc proteins, abrogates redox homeostasis, and deregulates cellular metalloproteome. To date, this displacement has been described mostly for cysteine(Cys)‐rich intraprotein binding sites in certain zinc finger domains and metallothioneins. To visualize how a Zn II ‐to‐Cd II swap can affect the target protein's status and thus understand the molecular basis of Cd II ‐induced genotoxicity an intermolecular Zn II ‐binding site from the crucial DNA repair protein Rad50 and its zinc hook domain were examined. By using a length‐varied peptide base, Zn II ‐to‐Cd II displacement in Rad50’s hook domain is demonstrated to alter it in a bimodal fashion: 1) Cd II induces around a two‐orders‐of‐magnitude stabilization effect (log K 12ZnII=20.8 vs. log K 12CdII=22.7), which defines an extremely high affinity of a peptide towards a metal ion, and 2) the displacement disrupts the overall assembly of the domain, as shown by NMR spectroscopic and anisotropy decay data. Based on the results, a new model explaining the molecular mechanism of Cd II genotoxicity that underlines Cd II ’s impact on Rad50’s dimer stability and quaternary structure that could potentially result in abrogation of the major DNA damage response pathway is proposed.