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Clathrin-mediated endocytosis is an essential cellular function in all eukaryotes that is driven by a self-assembled macromolecular machine of over 50 different proteins in tens to hundreds of copies. How these proteins are organized to produce endocytic vesicles with high precision and efficiency is not understood. Here, we developed high-throughput superresolution microscopy to reconstruct the nanoscale structural organization of 23 endocytic proteins from over 100,000 endocytic sites in yeast. We found that proteins assemble by radially ordered recruitment according to function. WASP family proteins form a circular nanoscale template on the membrane to spatially control actin nucleation during vesicle formation. Mathematical modeling of actin polymerization showed that this WASP nano-template optimizes force generation for membrane invagination and substantially increases the efficiency of endocytosis. Such nanoscale pre-patterning of actin nucleation may represent a general design principle for directional force generation in membrane remodeling processes such as during cell migration and division.
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http://dx.doi.org/10.1016/j.cell.2018.06.032 | DOI Listing |
PLoS Genet
September 2025
Department of Biochemistry, Indian Institute of Science, Bengaluru, Karnataka, India.
Tropomyosin is an actin-binding protein (ABP) which protects actin filaments from cofilin-mediated disassembly. Distinct tropomyosin isoforms have long been hypothesized to differentially sort to subcellular actin networks and impart distinct functionalities. Nevertheless, a mechanistic understanding of the interplay between Tpm isoforms and their functional contributions to actin dynamics has been lacking.
View Article and Find Full Text PDFPLoS One
September 2025
Department of Biology, The University of Saskatchewan, College of Arts and Science, Saskatoon, Canada.
Plasmodesmata are specialized structures in plant cell walls that mediate intercellular communication by regulating the trafficking of molecules between adjacent cells. The actin cytoskeleton plays a pivotal role in controlling plasmodesmatal permeability, but the molecular mechanisms underlying this regulation remain unclear. Here, we report that BRK1, a component of the WAVE/SCAR complex involved in Arp2/3-mediated actin nucleation, localizes to PD and primary pit fields in A.
View Article and Find Full Text PDFbioRxiv
August 2025
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA.
Many species undergo actin-based motility to promote cell-cell spread during infection. Rickettsial genomes encode two motility effectors, RickA and Sca2. In the spotted fever group species , RickA acts early in infection by activating the host Arp2/3 complex; Sca2 acts later by mimicking the structure and function of eukaryotic formins.
View Article and Find Full Text PDFJ Cell Sci
September 2025
Section of Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA.
Xenopus egg extracts can self-organize into cell-like compartments without the classic microtubule organizer centrosome. Compartment formation requires microtubules, but the organization of microtubules throughout the process remains unclear. Here, we show that the earliest organized microtubule structures to emerge during cell-like compartment formation are centrosome-independent asters.
View Article and Find Full Text PDFACS Med Chem Lett
August 2025
Division of Chemical Biology and Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, United States.
Wiskott-Aldrich syndrome protein family (WASF) members are key regulators of actin cytoskeleton dynamics at the leading edge of the cell membrane. WASF3 has been demonstrated to directly promote cancer invasion and metastasis in triple-negative breast cancer. WASF3 is incorporated into a heteropentameric protein complex with BRK1, CYFIP1/2, NCKAP1/1L, and ABI1/2/3 termed the WASF Regulatory Complex (WRC) that links upstream signaling pathways to Arp2/3-mediated actin nucleation.
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