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Mutations in PARK2 and PARK6 genes are responsible for the majority of hereditary Parkinson's disease cases. These genes encode the E3 ubiquitin ligase parkin and the protein kinase PTEN-induced kinase 1 (PINK1), respectively. Together, parkin and PINK1 regulate the mitophagy pathway, which recycles damaged mitochondria following oxidative stress. Native parkin is inactive and exists in an autoinhibited state mediated by its ubiquitin-like (UBL) domain. PINK1 phosphorylation of serine 65 in parkin's UBL and serine 65 of ubiquitin fully activate ubiquitin ligase activity; however, a structural rationale for these observations is not clear. Here, we report the structure of the phosphorylated UBL domain from parkin. We find that destabilization of the UBL results from rearrangements to hydrophobic core packing that modify its structure. Altered surface electrostatics from the phosphoserine group disrupt its intramolecular association, resulting in poorer autoinhibition in phosphorylated parkin. Further, we show that phosphorylation of both the UBL domain and ubiquitin are required to activate parkin by releasing the UBL domain, forming an extended structure needed to facilitate E2-ubiquitin binding. Together, the results underscore the importance of parkin activation by the PINK1 phosphorylation signal and provide a structural picture of the unraveling of parkin's ubiquitin ligase potential.
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http://dx.doi.org/10.1073/pnas.1613040114 | DOI Listing |
J Mol Biol
August 2025
Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada. Electronic address: https://www.biochem.uwo.ca/fac/shaw.
Parkin is a 52 kDa RING-Between-RING E3 ligase that ubiquitinates proteins at the outer mitochondrial membrane in response to oxidative stress. Part of a neuroprotective pathway, over 100 mutations in the PRKN gene have been associated with Early Onset Parkinson's Disease. To be fully active parkin requires interaction with phosphorylated ubiquitin and phosphorylation of its N-terminal Ubl domain, both dependent on the PINK1 kinase.
View Article and Find Full Text PDFCell Death Dis
August 2025
The National & Local Joint Engineering Laboratory of Animal Peptide Drug Development, College of Life Sciences, Hunan Normal University, Changsha, Hunan, 410081, China.
Glioblastoma (GBM), a World Health Organization (WHO) grade IV glioma, is one of the most lethal brain tumors, with a poor prognosis and limited treatment options. Temozolomide (TMZ), a first-line chemotherapeutic agent, often proves ineffective due to resistance and toxicity associated with overexpressed O-methylguanine-DNA-methyltransferase (MGMT). In this study, we identified ubiquitin-specific protease 7 (USP7) as a nuclear regulator of MGMT stability and TMZ resistance.
View Article and Find Full Text PDFBiochemistry
August 2025
MOE Key Laboratory for Cellular Dynamics, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Hefei National Laboratory for Physical Sciences at the Microscale, Biomedical Sciences and Health Laboratory of Anhui Province, Division of Life Sciences and Medicine, University of Scienc
Tail-anchored (TA) membrane proteins, defined by a single C-terminal transmembrane helix, are predominantly targeted to the endoplasmic reticulum (ER) via the post-translational GET pathway. While previous studies have characterized how chaperones shield the hydrophobic TA transmembrane domain (TMD), it remains unclear whether the cytosolic domain (TA) contributes to recognition. Here, we show that Sgt2, the entry chaperone of the GET pathway, engages TA proteins through a bipartite mechanism: its C-terminal domain captures the TMD, while its N-terminal domain (Sgt2) recognizes basic, α-helix-prone segments within TAs.
View Article and Find Full Text PDFSci Rep
July 2025
Federal University of Rio de Janeiro, CCMN, Chemistry Institute, Postgraduate Program in Chemistry - PGQu, Rio de Janeiro, RJ, 21941-853, Brazil.
We investigated statin-based peptidomimetic compounds as inhibitors of SARS-CoV-2 papain-like protease (PLpro) by in silico methods, including molecular docking/dynamic simulations and ADMET prediction, as well as enzymatic in vitro assays. Five compounds (LQMed 426, 428, 430, 431, and 432) were identified as having promising interactions with the active site and an allosteric site of PLpro. The docking poses in the active site revealed that the compounds interacted with the catalytic triad (Cys111, His272, and Asp286).
View Article and Find Full Text PDFBiochemistry
August 2025
Department of Integrative Structural and Computational Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd, La Jolla, California 92037, United States.
Members of the ATG8 family of ubiquitin-like proteins (Ubls) are covalently attached to phosphatidylethanolamine (PE) on nascent autophagosomal membranes, where they recruit cargo receptors and promote membrane expansion. Although the overall lipidation pathway is well established, the molecular details-particularly those involving the E2 enzyme ATG3-remain incompletely defined. Here, we uncover a previously unrecognized, noncovalent binding mode between the mammalian ATG8 protein GABARAP and the backside of ATG3's catalytic E2 domain.
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