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Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

ABSTRACT: PTEN is a dual-specificity protein tyrosine phosphatase. As one of the central tumor suppressors, a thorough regulation of its activity is essential for proper cellular homeostasis. The precise implications of PTEN inhibition by reactive oxygen species (e.g. H2 O2 ) and the subsequent structural consequences remain elusive. To study the effects of PTEN inhibition, bisperoxidovanadium (bpV) complexes serve as important tools with the potential for the treatment of nerve injury or cardiac ischemia. However, their mode of action is unknown, hampering further optimization and preventing therapeutic applications. Based on protein crystallography, mass spectrometry, and NMR spectroscopy, we elucidate the molecular basis of PTEN inhibition by H2O2 and bpV complexes. We show that both molecules inhibit PTEN via oxidative mechanisms resulting in the formation of the same intramolecular disulfide, therefore enabling the reactivation of PTEN under reductive conditions.

SUBMITTER: Lee CU

PROVIDER: S-EPMC4648047 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

Lee Chang-Uk CU Hahne Gernot G Hanske Jonas J Bange Tanja T Bier David D Rademacher Christoph C Hennig Sven S Grossmann Tom N TN

Angewandte Chemie (International ed. in English) 20150929 46

PTEN is a dual-specificity protein tyrosine phosphatase. As one of the central tumor suppressors, a thorough regulation of its activity is essential for proper cellular homeostasis. The precise implications of PTEN inhibition by reactive oxygen species (e.g. H2 O2 ) and the subsequent structural consequences remain elusive. To study the effects of PTEN inhibition, bisperoxidovanadium (bpV) complexes serve as important tools with the potential for the treatment of nerve injury or cardiac ischemia ...[more]

PMID: 26418532

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Project description:Preexposure to a low concentration of H2O2 significantly increases the survivability of catalase-negative streptococci in the presence of a higher concentration of H2O2 However, the mechanisms of this adaptation remain unknown. Here, using a redox proteomics assay, we identified 57 and 35 cysteine-oxidized proteins in Streptococcus oligofermentans bacteria that were anaerobically cultured and then pulsed with 40 μM H2O2 and that were statically grown in a 40-ml culture, respectively. The oxidized proteins included the peroxide-responsive repressor PerR, the manganese uptake repressor MntR, thioredoxin system proteins Trx and Tpx, and most glycolytic proteins. Cysteine oxidations of these proteins were verified through redox Western blotting, immunoprecipitation, and liquid chromatography-tandem mass spectrometry assays. In particular, Zn2+-coordinated Cys139 and Cys142 mutations eliminated the H2O2 oxidation of PerR, and inductively coupled plasma mass spectrometry detected significantly decreased amounts of Zn2+ in H2O2-treated PerR, demonstrating that cysteine oxidation results in Zn2+ loss. An electrophoretic mobility shift assay (EMSA) determined that the DNA binding of Mn2+-bound PerR protein (PerR:Zn,Mn) was abolished by H2O2 treatment but was restored by dithiothreitol reduction, verifying that H2O2 inactivates streptococcal PerR:Zn,Mn through cysteine oxidation, analogous to the findings for MntR. Quantitative PCR and EMSA demonstrated that tpx, mntA, mntR, and dpr belonged to the PerR regulons but that only dpr was directly regulated by PerR; mntA was also controlled by MntR. Deletion of mntR significantly reduced the low-H2O2-concentration-induced adaptation of S. oligofermentans to a higher H2O2 concentration, while the absence of PerR completely abolished the self-protection. Therefore, a low H2O2 concentration resulted in the cysteine-reversible oxidations of PerR and MntR to derepress their regulons, which function in cellular metal and redox homeostasis and which endow streptococci with the antioxidative capability. This work reveals a novel Cys redox-based H2O2 defense strategy employed by catalase-negative streptococci in Mn2+-rich cellular environments.IMPORTANCE The catalase-negative streptococci produce as well as tolerate high levels of H2O2 This work reports the molecular mechanisms of low-H2O2-concentration-induced adaptation to higher H2O2 stress in a Streptococcus species, in which the peroxide-responsive repressor PerR and its redox regulons play the major role. Distinct from the Bacillus subtilis PerR, which is inactivated by H2O2 through histidine oxidation by the Fe2+-triggered Fenton reaction, the streptococcal PerR is inactivated by H2O2 oxidation of the structural Zn2+ binding cysteine residues and thus derepresses the expression of genes defending against oxidative stress. The reversible cysteine oxidation could provide flexibility for PerR regulation in streptococci, and the mechanism might be widely used by lactic acid bacteria, including pathogenic streptococci, containing high levels of cellular manganese, in coping with oxidative stress. The adaptation mechanism could also be applied in oral hygiene by facilitating the fitness and adaptability of the oral commensal streptococci to suppress the pathogens.

Project description:Hydrogen peroxide (H2O2) is a key signaling agent. Its best characterized signaling actions in mammalian cells involve the early oxidation of thiols in cytoplasmic phosphatases, kinases and transcription factors. However, these redox targets are orders of magnitude less H2O2-reactive and abundant than cytoplasmic peroxiredoxins. How can they be oxidized in a signaling time frame? Here we investigate this question using computational reaction-diffusion models of H2O2 signaling. The results show that at H2O2 supply rates commensurate with mitogenic signaling a H2O2 concentration gradient with a length scale of a few tenths of μm is established. Even near the supply sites H2O2 concentrations are far too low to oxidize typical targets in an early mitogenic signaling time frame. Furthermore, any inhibition of the peroxiredoxin or increase in H2O2 supply able to drastically increase the local H2O2 concentration would collapse the concentration gradient and/or cause an extensive oxidation of the peroxiredoxins I and II, inconsistent with experimental observations. In turn, the local concentrations of peroxiredoxin sulfenate and disulfide forms exceed those of H2O2 by several orders of magnitude. Redox targets reacting with these forms at rate constants much lower than that for, say, thioredoxin could be oxidized within seconds. Moreover, the spatial distribution of the concentrations of these peroxiredoxin forms allows them to reach targets within 1 μm from the H2O2 sites while maintaining signaling localized. The recruitment of peroxiredoxins to specific sites such as caveolae can dramatically increase the local concentrations of the sulfenic and disulfide forms, thus further helping these species to outcompete H2O2 for the oxidation of redox targets. Altogether, these results suggest that H2O2 signaling is mediated by localized redox relays whereby peroxiredoxins are oxidized to sulfenate and disulfide forms at H2O2 supply sites and these forms in turn oxidize the redox targets near these sites.

Dataset Information

Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

Publications

Redox Modulation of PTEN Phosphatase Activity by Hydrogen Peroxide and Bisperoxidovanadium Complexes.

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