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Lambert, Talley

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Lambert

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Talley

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Lambert, Talley
Author's Publications: search.filters.isAuthorOfPublication.643eb45a-db0e-491d-b49e-3cc2634ce3b1

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    Polo-like kinase-dependent phosphorylation of the synaptonemal complex protein SYP-4 regulates double-strand break formation through a negative feedback loop.
    (eLife Sciences Publications, Ltd, 2017) Nadarajan, Saravanapriah; Lambert, Talley; Altendorfer, Elisabeth; Gao, Jinmin; Blower, Michael; Waters, Jennifer; Colaiacovo, Monica
    The synaptonemal complex (SC) is an ultrastructurally conserved proteinaceous structure that holds homologous chromosomes together and is required for the stabilization of pairing interactions and the completion of crossover (CO) formation between homologs during meiosis I. Here, we identify a novel role for a central region component of the SC, SYP-4, in negatively regulating formation of recombination-initiating double-strand breaks (DSBs) via a feedback loop triggered by crossover designation in C. elegans. We found that SYP-4 is phosphorylated dependent on Polo-like kinases PLK-1/2. SYP-4 phosphorylation depends on DSB formation and crossover designation, is required for stabilizing the SC in pachytene by switching the central region of the SC from a more dynamic to a less dynamic state, and negatively regulates DSB formation. We propose a model in which Polo-like kinases recognize crossover designation and phosphorylate SYP-4 thereby stabilizing the SC and making chromosomes less permissive for further DSB formation. DOI: http://dx.doi.org/10.7554/eLife.23437.001
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    Superresolution microscopy of the β-carboxysome reveals a homogeneous matrix
    (The American Society for Cell Biology, 2017) Niederhuber, Matthew J.; Lambert, Talley; Yapp, Clarence; Silver, Pamela; Polka, Jessica K.
    Carbon fixation in cyanobacteria makes a major contribution to the global carbon cycle. The cyanobacterial carboxysome is a proteinaceous microcompartment that protects and concentrates the carbon-fixing enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) in a paracrystalline lattice, making it possible for these organisms to fix CO2 from the atmosphere. The protein responsible for the organization of this lattice in beta-type carboxysomes of the freshwater cyanobacterium Synechococcus elongatus, CcmM, occurs in two isoforms thought to localize differentially within the carboxysome matrix. Here we use wide-field time-lapse and three-dimensional structured illumination microscopy (3D-SIM) to study the recruitment and localization of these two isoforms. We demonstrate that this superresolution technique is capable of distinguishing the localizations of the outer protein shell of the carboxysome and its internal cargo. We develop an automated analysis pipeline to analyze and quantify 3D-SIM images and generate a population-level description of the carboxysome shell protein, RuBisCO, and CcmM isoform localization. We find that both CcmM isoforms have similar spatial and temporal localization, prompting a revised model of the internal arrangement of the β-carboxysome.
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    Direction of actin flow dictates integrin LFA-1 orientation during leukocyte migration
    (Nature Publishing Group UK, 2017) Nordenfelt, Pontus; Moore, Travis; Mehta, Shalin B.; Kalappurakkal, Joseph Mathew; Swaminathan, Vinay; Koga, Nobuyasu; Lambert, Talley; Baker, David; Waters, Jennifer; Oldenbourg, Rudolf; Tani, Tomomi; Mayor, Satyajit; Waterman, Clare M.; Springer, Timothy
    Integrin αβ heterodimer cell surface receptors mediate adhesive interactions that provide traction for cell migration. Here, we test whether the integrin, when engaged to an extracellular ligand and the cytoskeleton, adopts a specific orientation dictated by the direction of actin flow on the surface of migrating cells. We insert GFP into the rigid, ligand-binding head of the integrin, model with Rosetta the orientation of GFP and its transition dipole relative to the integrin head, and measure orientation with fluorescence polarization microscopy. Cytoskeleton and ligand-bound integrins orient in the same direction as retrograde actin flow with their cytoskeleton-binding β-subunits tilted by applied force. The measurements demonstrate that intracellular forces can orient cell surface integrins and support a molecular model of integrin activation by cytoskeletal force. Our results place atomic, Å-scale structures of cell surface receptors in the context of functional and cellular, μm-scale measurements.