Zinc plays a vital role in structural, catalysis, and signal regulation in the human body. Zinc deficiency leads to the dysfunction of many organs and immunity systems. Diet proteins have distinct effects on zinc uptake. However, the mechanisms are uncovered. Here we select three principal components from whey protein: alpha-lactalbumin, beta-lactoglobulin, and bovine serum albumin, which bind with zinc at different affinities, to evaluate the relationship between their potential zinc uptake and protein binding. The experimental data shows that beta-lactoglobulin could promote zinc uptake, alpha-lactalbumin has minor effects, whereas bovine serum albumin reduced zinc uptake in Caco-2 cell lines. Zinc binding effects on protein structure were thoroughly inspected through fluorescent spectroscopy and X-ray crystallography. Isothermal titration calorimetry revealed that three proteins have different binding affinities toward zinc ions. We speculate that protein binding eliminates toxic effects from free zinc, and the binding strength dominates zinc uptake.
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http://dx.doi.org/10.1039/d2ra03565k | DOI Listing |
The human () gene encodes a plasma membrane protein SLC39A8 (ZIP8) that mediates the specific uptake of the metals Cd, Mn, Zn, Fe, Co, and Se Pathogenic variants within are associated with congenital disorder of glycosylation type 2 (CDG type II) or Leigh-like syndrome. However, numerous mutations of uncertain significance are also linked to different conditions or benign traits. Our study characterized 21 variants and measured their impact on protein localization and intracellular levels of Cd, Zn, and Mn We identified four variants that disrupt protein expression, five variants with high retention in the endoplasmic reticulum, and 12 variants with localization to the plasma membrane.
View Article and Find Full Text PDFNat Commun
January 2025
Institute of Medical Microbiology, University of Zurich, Zurich, Switzerland.
The mycobacterial ABC transporter IrtAB features an ABC exporter fold, yet it imports iron-charged siderophores called mycobactins. Here, we present extensive cryo-EM analyses and DEER measurements, revealing that IrtAB alternates between an inward-facing and an outward-occluded conformation, but does not sample an outward-facing conformation. When IrtAB is locked in its outward-occluded conformation in nanodiscs, mycobactin is bound in the middle of the lipid bilayer at a membrane-facing crevice opening at the heterodimeric interface.
View Article and Find Full Text PDFNanomicro Lett
January 2025
Shanghai Key Lab of Chemical Assessment and Sustainability, School of Chemical Science and Engineering, Tongji University, Shanghai, 200092, People's Republic of China.
bioRxiv
January 2025
Woods Hole Oceanographic Institution, Department of Marine Chemistry and Geochemistry, Woods Hole, MA.
Zinc is central to the function of many proteins, yet the mechanisms of zinc homeostasis and their interplay with other cellular systems remain underexplored. In this study, we employ data-dependent acquisition (DDA) and data-independent acquisition (DIA) mass spectrometry to investigate proteome changes in under conditions of different zinc availability. Using these methods, we detected 2143 unique proteins, 1578 of which were identified by both DDA and DIA.
View Article and Find Full Text PDFProtein Sci
February 2025
Department of Chemistry and Biochemistry, Center for RNA Biology, The Ohio State University, Columbus, Ohio, USA.
Loz1 is a zinc-responsive transcription factor in fission yeast that maintains cellular zinc homeostasis by repressing the expression of genes required for zinc uptake in high zinc conditions. Previous deletion analysis of Loz1 found a region containing two tandem CH zinc-fingers and an upstream "accessory domain" rich in histidine, lysine, and arginine residues to be sufficient for zinc-dependent DNA binding and gene repression. Here we report unexpected biophysical properties of this pair of seemingly classical CH zinc fingers.
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