Reactive oxygen species (ROS), released as byproducts of mitochondrial metabolism or as products of NADPH oxidases and other processes, can directly oxidize the active-site cysteine (Cys) residue of protein tyrosine phosphatases (PTPs) in a mammalian cell. Robust degradation of irreversibly oxidized PTPs is essential for preventing accumulation of these permanently inactive enzymes. However, the mechanism underlying the degradation of these proteins was unknown. In this study, we found that the active-site Cys215 of endogenous PTP1B is sulfonated in H9c2 cardiomyocytes under physiological conditions. The sulfonation of Cys215 led PTP1B to exhibit a conformational change, and drive the subsequent ubiquitination and degradation of this protein. We then discovered that Cullin1, an E3 ligase, interacts with the Cys215-sulfonated PTP1B. The functional impairment of Cullin1 prevented PTP1B from oxidation-dependent ubiquitination and degradation in H9c2 cells. Moreover, delivery of the terminally oxidized PTP1B resulted in proteotoxicity-caused injury in the affected cells. In conclusion, we elucidate how sulfonation of the active-site Cys215 can direct turnover of endogenous PTP1B through the engagement of ubiquitin-proteasome system. These data highlight a novel mechanism that maintains PTP homeostasis in cardiomyocytes with constitutive ROS production.
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http://dx.doi.org/10.1016/j.freeradbiomed.2022.11.041 | DOI Listing |
Anal Chim Acta
January 2025
Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE, USA. Electronic address:
Background: DJ-1 is a protein whose mutation causes rare heritable forms of Parkinson's disease (PD) and is of interest as a target for treating PD and other disorders. This work used high performance affinity microcolumns to screen and examine the binding of small molecules to DJ-1, as could be used to develop new therapeutics or to study the role of DJ-1 in PD. Non-covalent entrapment was used to place microgram quantities of DJ-1 in an unmodified form within microcolumns, which were then used in multiple studies to analyze binding by model compounds and possible drug candidates to DJ-1.
View Article and Find Full Text PDFBackground: Neurological disorders are at epidemic levels in the world today. Various proteins are being targeted for the development of novel molecular therapeutics; however, no small-molecule inhibitors have been discovered. Recent studies suggest that there are few molecules in clinical trials for various secretase (α, β, and γ), caspase, and calpain inhibitors.
View Article and Find Full Text PDFBiomolecules
November 2024
Department of Biology, Washington University, St. Louis, MO 63146, USA.
Mitochondrial holocytochrome c synthase (HCCS) is an essential protein in assembling cytochrome c (cyt c) of the electron transport system. HCCS binds heme and covalently attaches the two vinyls of heme to two cysteine thiols of the cyt c CXXCH motif. Human HCCS recognizes both cyt c and cytochrome c of complex III (cytochrome bc).
View Article and Find Full Text PDFFront Chem Biol
August 2024
Center for Structure-based Drug Design and Development, Department of Pharmaceutical Sciences, Concordia University Wisconsin, Mequon, WI, United States.
Introduction: Dual specific phosphatases (DUSPs) are mitogen-activated protein kinase (MAPK) regulators, which also serve as drug targets for treating various vascular diseases. Previously, we have presented mechanistic characterizations of DUSP5 and its interaction with pERK, proposing a dual active site.
Methods: Herein, we characterize the interactions between the DUSP5 phosphatase domain and the pT-E-pY activation loop of ERK2, with specific active site assignments.
Nat Commun
January 2025
National Institute for Physiological Sciences, National Institutes of Natural Sciences (NINS), Okazaki, Japan.
The presence of redox-active molecules containing catenated sulfur atoms (supersulfides) in living organisms has led to a review of the concepts of redox biology and its translational strategy. Glutathione (GSH) is the body's primary detoxifier and antioxidant, and its oxidized form (GSSG) has been considered as a marker of oxidative status. However, we report that GSSG, but not reduced GSH, prevents ischemic supersulfide catabolism-associated heart failure in male mice by electrophilic modification of dynamin-related protein (Drp1).
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