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Proteasomes degrade diverse proteins in different cellular contexts through incompletely defined regulatory mechanisms. Here we report the cryo-EM structure of human thioredoxin-like protein 1 (TXNL1) bound to the 19S regulatory particle of proteasomes via interactions with PSMD1 (Rpn2), PSMD4 (Rpn10) and PSMD14 (Rpn11). Proteasome binding is necessary for the ubiquitin-independent degradation of TXNL1 upon cellular exposure to metal- or metalloid-containing oxidative agents, thereby establishing a structural requirement for the stress-induced degradation of TXNL1.
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http://dx.doi.org/10.1038/s41594-025-01639-w | DOI Listing |
Nat Struct Mol Biol
August 2025
Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
Proteasomes degrade diverse proteins in different cellular contexts through incompletely defined regulatory mechanisms. Here we report the cryo-EM structure of human thioredoxin-like protein 1 (TXNL1) bound to the 19S regulatory particle of proteasomes via interactions with PSMD1 (Rpn2), PSMD4 (Rpn10) and PSMD14 (Rpn11). Proteasome binding is necessary for the ubiquitin-independent degradation of TXNL1 upon cellular exposure to metal- or metalloid-containing oxidative agents, thereby establishing a structural requirement for the stress-induced degradation of TXNL1.
View Article and Find Full Text PDFFree Radic Biol Med
October 2025
Liaoning Key Laboratory of Chemical Additive Synthesis and Separation (CASS) & School of Chemical Engineering, Ocean Technology and Life Science (CEOTLS) & Panjin Institute of Industrial Technology (PIIT), Dalian University of Technology, Panjin, 124221, China. Electronic address:
Cytosolic thioredoxin reductase (TXNRD1) is a key selenoenzyme involved in cellular redox regulation and antioxidant defense. Elucidating the catalytic mechanism of TXNRD1 and its conserved residues or domains is crucial for drug discovery and development. In this study, we investigated the functional roles of several conserved residues in TXNRD1, including Trp, Tyr, and residues in the guiding bar motif, and the catalytic C-terminal domain.
View Article and Find Full Text PDFbioRxiv
November 2024
California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA.
The 26S proteasome targets many cellular proteins for degradation during general homeostasis, protein quality control, and the regulation of vital processes. A broad range of proteasome-interacting cofactors thereby modulates these functions and aids in substrate degradation. Here, we solved several high-resolution structures of the redox active cofactor TXNL1 bound to the human 26S proteasome at saturating and sub-stoichiometric concentrations by time resolved cryo-EM.
View Article and Find Full Text PDFSci Total Environ
November 2024
College of Marine Sciences, South China Agricultural University, Guangzhou 510642, China; Institute of Eco-Environmental Research, Guangxi Academy of Sciences, Nanning 530007, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Guangzhou 510006, China. Electronic address: w
The toxic effects of nanoparticles have been increasingly investigated, but there has been limited research on amphibians, especially those of conservation value. This study examined the effects of different concentrations (0, 0.04, 0.
View Article and Find Full Text PDFRedox Biol
November 2023
Department of Selenoprotein Research and the National Tumor Biology Laboratory, National Institute of Oncology, 1122, Budapest, Hungary; Division of Biochemistry, Department of Medical Biochemistry, Karolinska Institutet, SE-171 77, Stockholm, Sweden. Electronic address:
TXNL1 (also named TRP32, for thioredoxin related protein of 32 kDa) is a cytosolic thioredoxin-fold protein expressed in all cell types and conserved from yeast to mammals, but with yet poorly known function. Here, we expressed and purified human TXNL1 together with several Cys-to-Ser variants, characterizing their enzymatic properties. TXNL1 could reduce disulfides in insulin, cystine and glutathione disulfide (GSSG) in reactions coupled to thioredoxin reductase (TXNRD1, TrxR1) using NADPH, similarly to thioredoxin (TXN, Trx1), but with lower catalytic efficacy due to at least one order of magnitude higher K of TrxR1 for TXNL1 compared to Trx1.
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