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Principal Investigator: Gira Bhabha
Organization: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
Fiscal Year: 2024
Award: $134,588
Funding agency: National Institute of Allergy and Infectious Diseases
Project Summary/Abstract
Microsporidia are unicellular, fungal parasites with a wide host-range, from insects to humans. They are
emerging pathogens, classified as NIAID Category B opportunistic pathogens, and cause microsporidiosis in
immunocompromised patients. To gain entry into a target cell, microsporidia employ a remarkably unique and
specialized harpoon-like invasion machinery called the polar tube, which is conserved among microsporidial
species. While initially coiled neatly within the spore of the parasite, infection of a new cell begins with the rapid
extrusion of the polar tube from the spore on a fast timescale (< 2s), which anchors the spore to the host cell.
After it has been fired, the polar tube is thought to act as a conduit for the transfer of the infectious
“sporoplasm” into the target cell, where replication can begin. Early work has yielded global insights into this
process, and the molecular and structural underpinnings of the invasion process are ripe for exploration with
modern techniques, such as cryo electron microscopy. This work aims to address fundamental questions and
paradoxes in our understanding of the microsporidial polar tube machinery and how it drives invasion into host
cells. We will use a combined bottom-up (structural biology, biochemistry and other in vitro techniques on
purified proteins) and top-down (in vivo light microscopy, electron tomography) approach; the intersection of
these approaches will allow us to unravel the mechanistic biology of this unique invasion process. Here we
focus on three human pathogens: Anncaliia algerae, Encephalitozoon cuniculi and Encephalitozoon hellem.
The specific aims are 1) To characterize the dynamics of polar tube firing and movement of sporoplasm
through the tube using high-speed optical microscopy, and to comprehensively define the composition of the
polar tube using mass spectrometry; 2) To biochemically and structurally characterize the individual protein
components of the polar tube organelle using X-ray crystallography, single particle cryo electron microscopy
and protein-protein interaction assays; 3) To elucidate the overall architecture and packing of the polar tube in
the spore using structural cell biology techniques such as serial block face scanning electron microscopy
(SBFSEM) and cryo focused ion beam scanning electron microscopy (cryo FIB-SEM) followed by cryo electron
tomography (cryo ET).
Terms: <3-D><3-Dimensional><3D><AIDS><Acquired Immune Deficiency><Acquired Immune Deficiency Syndrome><Acquired Immunodeficiency Syndrome><Address><Animals><Architecture><Assay><Bioassay><Biochemical><Biochemistry><Biological Assay><Biological Chemistry><Biology><Biophysics><Bombyx><Categories><Cell Body><Cells><Cellular biology><Cilia><Classification><Complex><Cryo-electron Microscopy><Cryo-electron tomography><Cryoelectron Microscopy><Data><Disease><Disorder><E hellem><E. hellem><Electron Cryomicroscopy><Encephalitozoon cuniculi><Encephalitozoon hellem><Engineering / Architecture><Environment><Face><Farm><Fishes><Fluorescence Agents><Fluorescent Agents><Fluorescent Dyes><Freezing><Generalized Growth><Growth><Human><Image><Immunocompromised><Immunocompromised Host><Immunocompromised Patient><Immunosuppressed Host><In Situ><In Vitro><Individual><Infection><Insecta><Insects><Insects Invertebrates><Invaded><Ions><Leanness><Light><Mass Photometry/Spectrum Analysis><Mass Spectrometry><Mass Spectroscopy><Mass Spectrum><Mass Spectrum Analyses><Mass Spectrum Analysis><Micro-tubule><Microscopy><Microspora><Microspora Infections><Microsporea><Microsporida><Microsporidia><Microsporidiosis><Microtubules><Modern Man><Modernization><Molecular><Molecular Configuration><Molecular Conformation><Molecular Stereochemistry><Movement><NIAID><Names><National Institute of Allergy and Infectious Disease><Nosema cuniculi><Optics><Organelles><Parasites><Patients><Photoradiation><Process><Protein Subunits><Proteins><Proteome><Reproduction spores><Resolution><Sampling><Scanning Electron Microscopy><Sequence Homology><Side><Silkmoths><Silkworms><Single Crystal Diffraction><Speed><Spores><Structure><Systematics><Techniques><Thinness><Tissue Growth><Tube><Visualization><Work><X Ray Crystallographies><X-Ray Crystallography><X-Ray Diffraction Crystallography><X-Ray/Neutron Crystallography><Xray Crystallography><biophysical foundation><biophysical principles><biophysical sciences><body movement><burden of disease><burden of illness><cell biology><conformation><conformational><conformational state><conformationally><conformations><cryo-EM><cryo-EM tomography><cryoEM><cryoEM tomography><cryoelectron tomography><cryogenic electron microscopy><disease burden><electron cryo-tomography><electron tomography><emerging pathogen><experiment><experimental research><experimental study><experiments><faces><facial><fluorescent dye/probe><gene manipulation><genetic manipulation><genetically manipulate><genetically perturb><human pathogen><imaging><immunosuppressed patient><in vivo><insight><light microscopy><light speed><lightspeed><mortality><name><named><naming><new pathogen><novel pathogen><ontogeny><opportunistic pathogen><optical><organ transplant patient><organ transplant recipient><particle><pathogen><protein complex><protein protein interaction><protein purification><reconstruction><resolutions><speed of light><structural biology><three dimensional>