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Zinc ions (Zn) are vital to most cells, with the intracellular concentrations of Zn being tightly regulated by multiple zinc transporters located at the plasma and organelle membranes. We herein present the 2.2-3.1 Å-resolution cryo-EM structures of a Golgi-localized human Zn/H antiporter ZnT7 (hZnT7) in Zn-bound and unbound forms. Cryo-EM analyses show that hZnT7 exists as a dimer via tight interactions in both the cytosolic and transmembrane (TM) domains of two protomers, each of which contains a single Zn-binding site in its TM domain. hZnT7 undergoes a TM-helix rearrangement to create a negatively charged cytosolic cavity for Zn entry in the inward-facing conformation and widens the luminal cavity for Zn release in the outward-facing conformation. An exceptionally long cytosolic histidine-rich loop characteristic of hZnT7 binds two Zn ions, seemingly facilitating Zn recruitment to the TM metal transport pathway. These structures permit mechanisms of hZnT7-mediated Zn uptake into the Golgi to be proposed.
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http://dx.doi.org/10.1038/s41467-023-40521-5 | DOI Listing |
Cell Res
September 2025
Department of Immunology, Center for Immunotherapy, Institute of Basic Medical Sciences, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
The pre-dimerization of endosome-localized RNA sensor Toll-like receptor 3 (TLR3) is required for its innate recognition, yet how TLR3 pre-dimers are formed and precisely primed for innate activation remains unclear. Here, we demonstrate that endosome-localized self RNA Rmrp directly binds to TLR3 and induces TLR3 dimerization in the early endosome but does not interact with endosome-localized TLR7, TLR8, TLR9 or cytoplasmic RNA sensor RIG-I under homeostatic conditions. Cryo-EM structure of Rmrp-TLR3 complex reveals a novel lapped conformation of TLR3 dimer engaged by Rmrp, which is distinct from the activation mechanism by dsRNA and the specific structural feature at the 3'-end of Rmrp is critical for its functional interaction with TLR3.
View Article and Find Full Text PDFFEBS J
September 2025
Department of Molecular Microbiology, John Innes Centre, Norwich, UK.
Understanding the molecular basis of regulated nitrogen (N) fixation is essential for engineering N-fixing bacteria that fulfill the demand of crop plants for fixed nitrogen, reducing our reliance on synthetic nitrogen fertilizers. In Azotobacter vinelandii and many other members of Proteobacteria, the two-component system comprising the anti-activator protein (NifL) and the Nif-specific transcriptional activator (NifA)controls the expression of nif genes, encoding the nitrogen fixation machinery. The NifL-NifA system evolved the ability to integrate several environmental cues, such as oxygen, nitrogen, and carbon availability.
View Article and Find Full Text PDFJ Biol Chem
September 2025
Department of Biochemistry and Molecular Biology, Penn State University, University Park, PA, 16802; Center for Structural Biology, Penn State University, University Park, PA 16802; Center for RNA Molecular Biology, Penn State University, University Park, PA 16802. Electronic address:
Despite the overall conservation of ribosomes across all domains of life, differences in their 3D architecture, rRNA sequences, ribosomal protein composition, and translation factor requirements reflect lineage-specific adaptations to environmental niches. In the domain Archaea, structural studies have primarily focused on non-methanogenic thermophiles and halophiles, leaving it unclear whether these represent the broader archaeal domain. Here, we report the cryo-electron microscopy (cryo-EM) structure of the ribosome from Methanosarcina acetivorans, a previously unreported high-resolution structure from a model mesophilic methanogenic archaeon.
View Article and Find Full Text PDFStructure
August 2025
Key Laboratory of Biomacromolecules (CAS), National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. Electronic address:
GABA (g-aminobutyric acid) transporter 3 (GAT3) is primarily found in glial cells and is essential for regulating GABA homeostasis in the central nervous system by mediating GABA uptake. Consequently, GAT3 has emerged as a significant therapeutic target for the treatment of epilepsy. In this study, we present the cryoelectron microscopy (cryo-EM) structures of GAT3 bound to its substrate GABA, the selective inhibitor SNAP-5114, and in the substrate-free state.
View Article and Find Full Text PDFMol Cell Proteomics
September 2025
Institute of Biotechnology, HiLIFE, Faculty of Medicine, University of Helsinki, Helsinki, Finland. Electronic address:
Structural proteomics has undergone a profound transformation, driven by the convergence of advanced experimental methodologies and computational innovations. Cutting-edge mass spectrometry (MS)-based approaches, including cross-linking MS (XL-MS), hydrogen-deuterium exchange MS (HDX-MS), and limited proteolysis MS (LiP-MS), now enable unprecedented insights into protein topology, conformational dynamics, and protein-protein interactions. These methods, complemented by affinity purification (AP), co-immunoprecipitation (co-IP), proximity labeling (PL), and spatial proteomics techniques, have expanded our ability to characterize the structural proteome at a systems-wide scale.
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