Working Paper Article Version 1 This version is not peer-reviewed

The Reactions of H2O2 and Gsno With the Zinc Finger Motif of Xpa. Not a Regulatory Mechanism, but No Synergy With Cadmium

Version 1 : Received: 20 August 2020 / Approved: 24 August 2020 / Online: 24 August 2020 (09:50:12 CEST)

A peer-reviewed article of this Preprint also exists.

Witkiewicz-Kucharczyk, A.; Goch, W.; Olędzki, J.; Hartwig, A.; Bal, W. The Reactions of H2O2 and GSNO with the Zinc Finger Motif of XPA. Not A Regulatory Mechanism, But No Synergy with Cadmium Toxicity. Molecules 2020, 25, 4177. Witkiewicz-Kucharczyk, A.; Goch, W.; Olędzki, J.; Hartwig, A.; Bal, W. The Reactions of H2O2 and GSNO with the Zinc Finger Motif of XPA. Not A Regulatory Mechanism, But No Synergy with Cadmium Toxicity. Molecules 2020, 25, 4177.

Journal reference: Molecules 2020, 25, 4177
DOI: 10.3390/molecules25184177

Abstract

Tetrathiolate zinc fingers are potential targets of oxidative assault under cellular stress conditions. We used the synthetic 37-residue peptide representing the tetrathiolate zinc finger domain of the DNA repair protein XPA, acetyl-DYVICEECGKEFMSYLMNHFDLPTCDNCRDADDKHK-amide (XPAzf) as a working model to study the reaction of its Zn(II) complex (ZnXPAzf) with hydrogen peroxide and S-nitrosoglutathione (GSNO), as oxidative and nitrosative stress agents, respectively. We also used the Cd(II) substituted XPAzf (CdXPAzf) to assess the situation of cadmium assault, which is accompanied by oxidative stress. Using electrospray mass spectrometry (ESI-MS), HPLC, and UV-vis and circular dichroism spectroscopies we demonstrated that even very low levels of H2O2 and GSNO invariably cause irreversible thiol oxidation and concomitant Zn(II) release from ZnXPAzf. In contrast, CdXPAzf was more resistant to oxidation, demonstrating the absence of synergy between cadmium and oxidative stresses. Our results indicate that GSNO cannot act as a reversible modifier of XPA, and rather has a deleterious effect on DNA repair.

Subject Areas

XPAzf; Zn; Cd; GSNO; H2O2; oxidation

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