Dynamic trafficking of G protein-coupled receptors (GPCRs) out of cilia is mediated by the BBSome. In concert with its membrane recruitment factor, the small GTPase ARL6/BBS3, the BBSome ferries GPCRs across the transition zone, a diffusion barrier at the base of cilia. Here, we present the near-atomic structures of the BBSome by itself and in complex with ARL6, and we describe the changes in BBSome conformation induced by ARL6 binding. Modeling the interactions of the BBSome with membranes and the GPCR Smoothened (SMO) reveals that SMO, and likely also other GPCR cargoes, must release their amphipathic helix 8 from the membrane to be recognized by the BBSome.
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http://dx.doi.org/10.7554/eLife.55954 | DOI Listing |
Nat Commun
January 2025
Center for Electron Microscopy, South China University of Technology, Guangzhou, China.
Electron ptychography, recognized as an ideal technique for low-dose imaging, consistently achieves deep sub-angstrom resolution at electron doses of several thousand electrons per square angstrom (e/Å) or higher. Despite its proven efficacy, the application of electron ptychography at even lower doses-necessary for materials highly sensitive to electron beams-raises questions regarding its feasibility and the attainable resolution under such stringent conditions. Herein, we demonstrate the implementation of near-atomic-resolution ( ~ 2 Å) electron ptychography reconstruction at electron doses as low as ~100 e/Å, for metal-organic frameworks (MOFs), which are known for their extreme sensitivity.
View Article and Find Full Text PDFNature
January 2025
Department of Biochemistry, University of Washington, Seattle, WA, USA.
Snakebite envenoming remains a devastating and neglected tropical disease, claiming over 100,000 lives annually and causing severe complications and long-lasting disabilities for many more. Three-finger toxins (3FTx) are highly toxic components of elapid snake venoms that can cause diverse pathologies, including severe tissue damage and inhibition of nicotinic acetylcholine receptors, resulting in life-threatening neurotoxicity. At present, the only available treatments for snakebites consist of polyclonal antibodies derived from the plasma of immunized animals, which have high cost and limited efficacy against 3FTxs.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea.
Recent advances in cryo-electron microscopy (cryo-EM) have facilitated the high-resolution structural determination of macromolecular complexes in their native states, providing valuable insights into their dynamic behaviors. However, insufficient understanding or experience with the cryo-EM image processing parameters can result in the loss of biological meaning. In this paper, we investigate the dihydrolipoyl acetyltransferase (E2) inner core complex of the pyruvate dehydrogenase complex (PDC) and reconstruct the 3D maps using five different symmetry parameters.
View Article and Find Full Text PDFbioRxiv
December 2024
Simons Machine Learning Center, New York Structural Biology Center, New York, United States.
It is now possible to generate large volumes of high-quality images of biomolecules at near-atomic resolution and in near-native states using cryogenic electron microscopy/electron tomography (Cryo-EM/ET). However, the precise annotation of structures like filaments and membranes remains a major barrier towards applying these methods in high-throughput. To address this, we present TARDIS (ransformer-bsed apid imensionless nstance egmentation), a machine-learning framework for fast and accurate annotation of micrographs and tomograms.
View Article and Find Full Text PDFCytoskeleton (Hoboken)
January 2025
Department of Biological Sciences, Graduate School of Science, Osaka University, Osaka, Japan.
Dyneins are huge motor protein complexes that are essential for cell motility, cell division, and intracellular transport. Dyneins are classified into three major subfamilies, namely cytoplasmic, intraflagellar-transport (IFT), and ciliary dyneins, based on their intracellular localization and functions. Recently, several near-atomic resolution structures have been reported for cytoplasmic/IFT dyneins.
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