Abstract
Intercellular tight junctions define epithelial apicobasal polarity and form a physical fence which protects underlying tissues from pathogen invasions. PALS1, a tight junction-associated protein, is a member of the CRUMBS3-PALS1-PATJ polarity complex, which is crucial for the establishment and maintenance of epithelial polarity in mammals. Here we report that the carboxy-terminal domain of the SARS-CoV E small envelope protein (E) binds to human PALS1. Using coimmunoprecipitation and pull-down assays, we show that E interacts with PALS1 in mammalian cells and further demonstrate that the last four carboxy-terminal amino acids of E form a novel PDZ-binding motif that binds to PALS1 PDZ domain. PALS1 redistributes to the ERGIC/Golgi region, where E accumulates, in SARS-CoV-infected Vero E6 cells. Ectopic expression of E in MDCKII epithelial cells significantly alters cyst morphogenesis and, furthermore, delays formation of tight junctions, affects polarity, and modifies the subcellular distribution of PALS1, in a PDZ-binding motif-dependent manner. We speculate that hijacking of PALS1 by SARS-CoV E plays a determinant role in the disruption of the lung epithelium in SARS patients.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Binding Sites
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Cell Line
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Chlorocebus aethiops
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Epithelial Cells / cytology
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Epithelial Cells / metabolism*
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Epithelial Cells / virology
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Epithelium / growth & development
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Epithelium / metabolism
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Glutathione Transferase
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HEK293 Cells
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Host-Pathogen Interactions
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Humans
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Immunoblotting
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Membrane Proteins / genetics
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Membrane Proteins / metabolism*
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Microscopy, Fluorescence
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Morphogenesis
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Nucleoside-Phosphate Kinase / genetics
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Nucleoside-Phosphate Kinase / metabolism*
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Protein Binding
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Severe acute respiratory syndrome-related coronavirus / metabolism
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Severe acute respiratory syndrome-related coronavirus / physiology
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Tight Junctions / metabolism*
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Tight Junctions / virology
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Two-Hybrid System Techniques
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Vero Cells
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Viral Envelope Proteins / genetics
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Viral Envelope Proteins / metabolism*
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Viroporin Proteins
Substances
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E protein, SARS coronavirus
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Luminescent Proteins
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Membrane Proteins
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Recombinant Fusion Proteins
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Viral Envelope Proteins
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Viroporin Proteins
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Glutathione Transferase
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Nucleoside-Phosphate Kinase
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MPP5 protein, human