Effects of metal ions on the activity of protein tyrosine phosphatase VHR: highly potent and reversible oxidative inactivation by Cu2+ ion.

Abstract

The posttranslational regulation of protein tyrosine phosphatases (PTPs) has been suggested to have a crucial role in maintaining the phosphotyrosine level in cells. Here we examined the regulatory effects of metal ions on human dual-specificity vaccinia H1-related protein tyrosine phosphatase (VHR) in vitro. Among various metal ions examined, Fe3+, Cu2+, Zn2+, and Cd2+ exerted their inactivational effects on VHR, and Cu2+ is the most potent inactivator. The VHR activity inactivated by the metal ions except Cu2+ was significantly restored by EDTA. The efficacy of Cu2+ for the VHR inactivation was about 200-fold more potent than that of H2O2. Cu2+ also inactivated other PTPs including PTP1B and SHP-1. The Cu2+-mediated inactivation at the submicromolar range was eradicated by dithiothreitol treatment. The loss of VHR activity correlated with the decreased [14C]iodoacetate labeling of active-site cysteine, suggesting that Cu2+ brought about the oxidation of the active-site cysteine. On the contrary, Zn2+ that exerted an inactivational effect at millimolar concentrations appeared not directly linked to the active-site cysteine, as indicated by the fact that [14C]iodoacetate labeling was unaffected and that the effect of Zn2+ on the Y78F mutant was increased. The reduction potential of VHR was estimated to be -331 mV by utilizing the reversibility of the redox state of VHR. Thus, we conclude that the highly potent Cu2+ inactivation of VHR is a consequence of the oxidation of the active-site cysteine and the mode of Zn2+ inactivation is distinct from that of Cu2+.

• Authors: J H Kim, H Cho, S E Ryu, M U Choi
• Journal: Archives of biochemistry and biophysics (Arch Biochem Biophys) Vol. 382 Issue 1 Pg. 72-80 (Oct 01 2000) ISSN: 0003-9861 [Print] United States
• PMID: 11051099 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Ions
• Copper
• Hydrogen Peroxide
• DUSP3 protein, human
• Dual Specificity Phosphatase 3
• Protein Tyrosine Phosphatases
• Glutathione
• Zinc
• Cysteine
• Oxygen
• Dithiothreitol

Topics

• Binding Sites
• Copper (metabolism)
• Cysteine (chemistry)
• Dithiothreitol (pharmacology)
• Dose-Response Relationship, Drug
• Dual Specificity Phosphatase 3
• Electrophoresis, Polyacrylamide Gel
• Enzyme Activation
• Glutathione (metabolism)
• Hydrogen Peroxide (pharmacology)
• Ions
• Mass Spectrometry
• Models, Chemical
• Mutagenesis, Site-Directed
• Oxygen (metabolism)
• Protein Tyrosine Phosphatases (antagonists & inhibitors, metabolism)
• Time Factors
• Zinc (metabolism)