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IFITM3 requires an amphipathic helix for antiviral activity
Nicholas M Chesarino1, Alex A Compton2,3,4, Temet M McMichael1
1Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH, USA.
EMBO Reports
|August 25, 2017
Summary
Interferon-induced transmembrane protein 3 (IFITM3) uses a specific helix to block viruses from entering cells. This amphipathic helix is crucial for IFITM3
Area of Science:
- Virology and Molecular Biology
- Cellular and Membrane Biology
- Bioinformatics and Structural Biology
Background:
- Interferon-induced transmembrane protein 3 (IFITM3) is a key cellular antiviral factor.
- IFITM3's mechanism for blocking virus-cell membrane fusion remains incompletely understood.
- Previous research suggested IFITM3 functions within transmembrane domains.
Purpose of the Study:
- To elucidate the precise mechanism by which IFITM3 inhibits viral entry.
- To identify structural elements within IFITM3 critical for its antiviral activity.
- To determine if this mechanism is conserved across different IFITM proteins.
Main Methods:
- Bioinformatic analysis to predict IFITM3 secondary structures.
- Identification and characterization of a conserved amphipathic helix.
- Functional assays using various viruses (influenza, Zika, VSV, Ebola, HIV) to assess antiviral inhibition.
Main Results:
- A conserved, short amphipathic helix was identified in a previously assumed transmembrane region of IFITM3.
- This amphipathic helix is essential for IFITM3's broad-spectrum antiviral activity against multiple viruses.
- The homologous helix in IFITM1 is also required for antiviral function, suggesting a conserved mechanism.
Conclusions:
- IFITM proteins, including IFITM3, employ a conserved amphipathic helix mechanism to inhibit virus fusion.
- This helix directly interferes with viral hemagglutinin-mediated membrane fusion.
- The findings reveal a novel structural basis for IFITM-mediated antiviral defense.
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