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Basic Characteristics of Mutations
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Mutation Site
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N82W |
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Mutation Site Sentence
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Finally, ORF3a expression in HEK293 cells leads to lysosomal volume increase, mitochondrial damage, and accumulation of intracellular membranes, all alterations reverted by the N82W mutation. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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ORF3a |
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Standardized Encoding Gene
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ORF3a
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Genotype/Subtype
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- |
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Viral Reference
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-
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Functional Impact and Mechanisms
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Disease
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Cell line
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Immune
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- |
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Target Gene
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-
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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39905220
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Title
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SARS-CoV-2 ORF3a accessory protein is a water-permeable channel that induces lysosome swelling
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Author
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Michelucci A,Sforna L,Focaia R,Leonardi MV,Di Battista A,Rastelli G,Vespa S,Boncompagni S,Di Cristina M,Catacuzzeno L
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Journal
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Communications biology
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Journal Info
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2025 Feb 4;8(1):170
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Abstract
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ORF3a, the most abundantly expressed accessory protein of SARS-CoV-2, plays an essential role in virus egress by inactivating lysosomes through their deacidification. However, the mechanism underlying this process remains unclear. While seminal studies suggested ORF3a being a cation-selective channel (i.e., viroporin), recent works disproved this conclusion. To unravel the potential function of ORF3a, here we employed a multidisciplinary approach including patch-clamp electrophysiology, videoimaging, molecular dynamics (MD) simulations, and electron microscopy. Preliminary structural analyses and patch-clamp recordings in HEK293 cells rule out ORF3a functioning as either viroporin or proton (H(+)) channel. Conversely, videoimaging experiments demonstrate that ORF3a mediates the transmembrane transport of water. MD simulations identify the tetrameric assembly of ORF3a as the functional water transporter, with a putative selectivity filter for water permeation that includes two essential asparagines, N82 and N119. Consistent with this, N82L and N82W mutations abolish ORF3a-mediated water permeation. Finally, ORF3a expression in HEK293 cells leads to lysosomal volume increase, mitochondrial damage, and accumulation of intracellular membranes, all alterations reverted by the N82W mutation. We propose a novel function for ORF3a as a lysosomal water-permeable channel, essential for lysosome deacidification and inactivation, key steps to promote virus egress.
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Sequence Data
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-
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