To elucidate the mechanisms of cuproprotein biosynthesis in the secretory pathway, a polyclonal antiserum was generated against hephaestin, a multicopper oxidase essential for enteric iron absorption. Immunoblot analysis and pulse-chase metabolic labeling revealed that hephaestin is synthesized as a single-chain polypeptide modified by N-linked glycosylation to a mature 161-kDa species. Cell surface biotinylation and immunofluorescent studies of polarized, differentiated colon carcinoma cells detected hephaestin on the basolateral surface under steady-state conditions. However, a decrease in the intracellular copper concentration resulted in a marked diminution in the abundance of this protein. Metabolic studies revealed no effect of decreased intracellular copper on the rate of hephaestin synthesis but a dramatic, specific, and reproducible increase in the turnover of the mature 161-kDa protein. Surprisingly, inhibitor studies revealed that this turnover occurs exclusively in the proteasome, and consistent with this finding, in vitro studies identified polyubiquitinated hephaestin under conditions abrogating copper incorporation into this protein. Taken together, these studies demonstrate the presence of a quality control system for posttranslational protein modification occurring beyond the endoplasmic reticulum that, in the case of hephaestin, directly links the rate of enteric iron uptake to nutritional copper status.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1074/jbc.M401151200 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Nitrous oxide production via enzymatic nitroxyl from the nitrifying archaeon .
Proc Natl Acad Sci U S A
January 2025
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853.
Ammonia oxidizing archaea (AOA) are among the most abundant microorganisms on earth and are known to be a major source of nitrous oxide (NO) emissions, although biochemical origins of this NO remain unknown. Enzymological details of AOA nitrogen metabolism are broadly unavailable. We report the recombinant expression, purification, and characterization of a multicopper oxidase, Nmar_1354, from the AOA .
View Article and Find Full Text PDFActive site-inspired multicopper laccase-like nanozymes for detection of phenolic and catecholamine compounds.
Anal Chim Acta
January 2025
School of Medical Devices, Shenyang Pharmaceutical University, No. 103, Wenhua Road, Shenyang, 110016, PR China. Electronic address:
Phenolic compounds are typical organic pollutants which cause severe human health problems due to their teratogenesis, carcinogenesis, neurotoxicity, immunotoxicity and endocrine disruption. Natural laccase is a multicopper oxidase existing in bacteria, plants, and insects, which can accelerate the transformation of phenolic compounds to their less hazardous oxidized products under mild conditions without harmful byproducts. Despite eco-environmentally friendly property of laccase, it still faces constraints of widespread application attribute to its high cost, complex preparation, and vulnerability.
View Article and Find Full Text PDFInfluence of Ligand Complexity on the Spectroscopic Properties of Type 1 Copper Sites: A Theoretical Study.
J Comput Chem
January 2025
Department of Mechanical Engineering, Texas Tech University, Lubbock, Texas, USA.
Multi-copper oxidases (MCOs) are enzymes of significant interest in biotechnology due to their efficient catalysis of oxygen reduction to water, making them valuable in sustainable energy production and bio-electrochemical applications. This study employs time-dependent density functional theory (TDDFT) to investigate the electronic structure and spectroscopic properties of the Type 1 (T1) copper site in Azurin, which serves as a model for similar sites in MCOs. Four model complexes of varying complexity were derived from the T1 site, including 3 three-coordinate models and 1 four-coordinate model with axial methionine ligation, to explore the impact of molecular branches and axial coordination.
View Article and Find Full Text PDFEngineering a Binding Peptide for Oriented Immobilization and Efficient Bioelectrocatalytic Oxygen Reduction of Multicopper Oxidases.
ACS Appl Mater Interfaces
January 2025
Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.
Enzymatic fuel cells (EFCs) are emerging as promising technologies in renewable energy and biomedical applications, utilizing enzyme catalysts to convert the chemical energy of renewable biomass into electrical energy, known for their high energy conversion efficiency and excellent biocompatibility. Currently, EFCs face challenges of poor stability and catalytic efficiency at the cathodes, necessitating solutions to enhance the oriented immobilization of multicopper oxidases for improved heterogeneous electron transfer efficiency. This study successfully identified a surface-binding peptide (SBP, 13 amino acids) derived from a methionine-rich fragment (MetRich, 53 amino acids) in CueO through semirational design.
View Article and Find Full Text PDFPrecision Thermostability Predictions: Leveraging Machine Learning for Examining Laccases and Their Associated Genes.
Int J Mol Sci
December 2024
International Ph.D. Program in Biomedical Engineering, College of Biomedical Engineering, Taipei Medical University, Taipei 11031, Taiwan.
Laccases, multi-copper oxidases, play pivotal roles in the oxidation of a variety of substrates, impacting numerous biological functions and industrial processes. However, their industrial adoption has been limited by challenges in thermostability. This study employed advanced computational models, including random forest (RF) regressors and convolutional neural networks (CNNs), to predict and enhance the thermostability of laccases.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!