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Histidine residues have been hypothesized to function as sensors of environmental pH that can trigger the activity of viral fusion proteins. We investigated a requirement for histidine residues in the envelope (E) protein of West Nile virus during pH-dependent entry into cells. Each histidine was individually replaced with a nonionizable amino acid and tested functionally. In each instance, mutants capable of orchestrating pH-dependent infection were identified. These results do not support a requirement for any single histidine as a pH-sensing "switch," and they suggest that additional features of the E protein are involved in triggering pH-dependent steps in the flavivirus life cycle.
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http://dx.doi.org/10.1128/JVI.01072-09 | DOI Listing |
Biochem Pharmacol
September 2025
Division of Biochemistry, National Institute of Health Sciences, Tonomachi 3-25-26, Kawasaki-ku, Kawasaki, Kanagawa 210-9501, Japan. Electronic address:
Liver X receptors (LXRα and LXRβ) are nuclear receptors critical for lipid homeostasis and inflammation regulation, making them potential therapeutic targets for atherosclerosis and inflammatory diseases. While LXR agonists hold promise, their use is limited by adverse effects on hepatic lipogenesis. Riccardin C (RC) has shown promise as an LXRα partial agonist/ LXRβ antagonist with cell-type-selective properties.
View Article and Find Full Text PDFJ Biol Chem
September 2025
Research Unit in Biology of Microorganisms (URBM), Department of Biology, Namur Research Institute for Life Sciences (NARILIS), University of Namur, Namur, Belgium.
Metals like copper (Cu), zinc, and nickel exhibit dual nature, necessitating a tight regulation of their cellular homeostasis to meet physiological demands while preventing toxicity. In bacteria, metal homeostasis involves inner membrane (IM) P-type ATPases and ABC transporters, envelope-spanning tripartite efflux pumps, and outer membrane (OM) pore-forming proteins. Four decades ago, the OM β-barrel protein PcoB was shown to provide an additional layer of Cu resistance in an Escherichia coli strain isolated from the gut of swine fed with Cu supplements.
View Article and Find Full Text PDFRSC Adv
August 2025
Department of Chemistry, University of California, Davis One Shields Avenue Davis CA 95616 USA
Imbalances in cellular copper are increasingly implicated in metabolic disorders. Food-derived peptides are gaining attention for their ability to alleviate metabolic disease symptoms with little to no toxicity. In this work, we enriched copper-binding peptides from enzymatic digestions of rice bran protein hydrolysates Cu(ii)-based immobilized-metal affinity-based separations, identified the sequences by mass spectrometry, and performed physicochemical and sequence analysis of the enriched peptides.
View Article and Find Full Text PDFbioRxiv
August 2025
Department of Biochemistry and Molecular Biology, Michigan State University, MI, USA.
The nickel pincer nucleotide (NPN) cofactor catalyzes the racemization/epimerization of α-hydroxy acids in enzymes of the LarA family. The established proton-coupled hydride transfer mechanism requires two catalytic histidine residues that alternately act as general acids and general bases. Notably, however, a fraction of LarA homologs (LarAHs) lack one of the active site histidine residues, replacing it with an asparaginyl side chain that cannot participate in acid/base catalysis.
View Article and Find Full Text PDFPLoS One
September 2025
Department of Neuroscience, University of Texas at Austin, Austin, Texas, United States of America.
The Transient Receptor Potential Vanilloid sub-type 1 (TRPV1) is an ion channel that is activated by heat, extracellular protons, oxidation, and it is implicated in various aspects of inflammatory pain. In this study, we uncover that residue M308 in the TRPV1 ankyrin repeat domain (ARD) stands out from most other buried ARD residues because of the greater number of human missense variants at this position while maintaining a high degree of conservation across species and TRPV channel subtypes. We use mutagenesis and electrophysiology to examine this apparent discrepancy and show that substitutions at position M308 that preserve or reduce side-chain volume have no effect on channel function, whereas substitutions with larger or more polar residues increase channel activity in response to capsaicin or temperature.
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