ACS Catal
Ciechanover Institute of Precision and Regenerative Medicine, School of Medicine, Chinese University of Hong Kong Shenzhen 518172, China.
Published: November 2023
The 20S proteasome is an attractive drug target for the development of anticancer agents because it plays an important role in cellular protein degradation. It has a threonine residue that can act as a nucleophile to attack inhibitors with an electrophilic warhead, forming a covalent adduct. Fundamental understanding of the reaction mechanism between covalent inhibitors and the proteasome may assist the design and refinement of compounds with the desired activity. In this study, we investigated the covalent inhibition mechanism of an -keto phenylamide inhibitor of the proteasome. We calculated the noncovalent binding free energy using the PDLD/S-LRA/ method and the reaction free energy through the empirical valence bond method (EVB). Several possible reaction pathways were explored. Subsequently, we validated the calculated activation and reaction free energies of the most plausible pathways by performing kinetic experiments. Furthermore, the effects of different ionization states of Asp17 on the activation energy at each step were also discussed. The results revealed that the ionization states of Asp17 remarkably affect the activation energies and there is an electrostatic reorganization of Asp17 during the course of the reaction. Our results demonstrate the critical electrostatic effect of Asp17 in the active site of the 20S proteasome.
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http://dx.doi.org/10.1021/acscatal.3c03538 | DOI Listing |
Proc Natl Acad Sci U S A
January 2025
Department of Medical Neuroscience, SUSTech Center for Pain Medicine, School of Medicine, Southern University of Science and Technology, Shenzhen 518055, China.
Ubiquitin-proteasomal degradation of K/Cl cotransporter 2 (KCC2) in the ventral posteromedial nucleus (VPM) has been demonstrated to serve as a common mechanism by which the brain emerges from anesthesia and regains consciousness. Ubiquitin-proteasomal degradation of KCC2 during anesthesia is driven by E3 ligase Fbxl4. However, the mechanism by which ubiquitinated KCC2 is targeted to the proteasome has not been elucidated.
View Article and Find Full Text PDFSci Adv
January 2025
Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, Hubei, China.
The proteasome degrades most superfluous and damaged proteins, and its decline is associated with many diseases. As the proteolytic unit, the 20 proteasome is assembled from 28 subunits assisted by chaperones PAC1/2/3/4 and POMP; then, it undergoes the maturation process, in which the proteolytic sites are activated and the assembly chaperones are cleared. However, mechanisms governing the maturation remain elusive.
View Article and Find Full Text PDFSheng Li Xue Bao
December 2024
Department of Orthopaedics, the First Hospital of Lanzhou University, Lanzhou 730000, China.
The maintenance of skeletal muscle quality involves various signal pathways that interact with each other. Under normal physiological conditions, these intersecting signal pathways regulate and coordinate the hypertrophy and atrophy of skeletal muscles, balancing the protein synthesis and degradation of muscle. When the total rate of protein synthesis exceeds that of protein degradation, the muscle gradually becomes enlarged, while when the total rate of protein synthesis is lower than that of protein degradation, the muscle shrinks.
View Article and Find Full Text PDFSheng Li Xue Bao
December 2024
Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Wenzhou 325000, China.
The N-end rule pathway is a protein degradation pathway mediated by the ubiquitin-proteasome system, which specifically targets and degrades target proteins by recognizing specific residues at the N-terminus of the proteins. The residues which play a crucial role in the N-end rule pathway are called degrons, also known as N-degrons, as they are usually unstable at the N-terminal end of the protein. Currently, several N-end rule pathways have been identified in the eukaryotes, including the Arg/N-end rule, Ac/N-end rule, and Pro/N-end rule pathways, as well as the recently discovered Gly/N-end rule pathway.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, 35131 Padova, Italy.
Limb-girdle muscular dystrophy type 2E/R4 (LGMD2E/R4) is a rare disease that currently has no cure. It is caused by defects in the gene, mainly missense mutations, which cause the impairment of the sarcoglycan complex, membrane fragility, and progressive muscle degeneration. Here, we studied the fate of some β-sarcoglycan (β-SG) missense mutants, confirming that, like α-SG missense mutants, they are targeted for degradation through the ubiquitin-proteasome system.
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