Reaction of the XPA zinc finger with S-nitrosoglutathione.
S-Nitrosoglutathione (GSNO) is an intracellular redox signaling molecule, also implicated in nitrosative stress. GSNO actions include modifications of Cys thiols in proteins. In this study, we focused on a GSNO reaction with a Cys4 zinc finger (ZF) sequence of human protein XPA, crucial to the nucleotide excision repair pathway of DNA repair. By using a corresponding synthetic 37-residue peptide acetyl-DYVICEECGKEFMDSYLMNHFDLPTCDNCRDADDKHK-amide (XPAzf) and combining the detection of noncovalent and covalent complexes by ESI-MS with zinc release monitored by the zinc-sensitive chromophore 4-(2-pyridylazo)resorcinol (PAR), we demonstrated that the reaction of XPAzf with GSNO yielded S-nitrosylated intermediates, intrapeptide disulfides, and mixed glutathione disulfides. The reaction started with the formation of a complex of GSNO with ZnXPAzf followed by thiol transnitrosylation reactions and the final formation of disulfides. The results obtained suggest that at low levels/transient exposures, GSNO may act as a reversible regulator of Cys4 ZF activity, whereas transnitrosylation by GSNO, occurring at prolonged exposures, may cause deleterious effects to the functions of Cys 4 ZF proteins. In the case of XPA, this may lead to DNA repair inhibition.
Smirnova
Julia
J
Department of Gene Technology, Tallinn Technical University, Akadeemia tee 15, 12618 Tallinn, Estonia.
Zhukova
Liliya
L
Witkiewicz-Kucharczyk
Aleksandra
A
Kopera
Edyta
E
Oledzki
Jacek
J
Wysłouch-Cieszyńska
Aleksandra
A
Palumaa
Peep
P
Hartwig
Andrea
A
Bal
Wojciech
W
D003545:Cysteine / Q000737:chemistry; D004260:DNA Repair; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000737:chemistry; D026422:S-Nitrosoglutathione / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D051760:Xeroderma Pigmentosum Group A Protein / Q000737:chemistry*; D015032:Zinc / Q000032:analysis / Q000737:chemistry; D016335:Zinc Fingers
D010446:Peptide Fragments; C497314:XPA protein, human; D051760:Xeroderma Pigmentosum Group A Protein; D026422:S-Nitrosoglutathione; D015032:Zinc; D003545:Cysteine