Cryo-EM analysis of a feline coronavirus spike protein reveals a unique structure and camouflaging glycans

Feline infectious peritonitis virus (FIPV) is an alphacoronavirus that causes a nearly 100% mortality rate without effective treatment. Here we report a 3.3-Å cryoelectron microscopy (cryo-EM) structure of the serotype I FIPV spike (S) protein, which is responsible for host recognition and viral ent...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2020-01, Vol.117 (3), p.1438-1446
Main Authors: Yang, Tzu-Jing, Chang, Yen-Chen, Ko, Tzu-Ping, Draczkowski, Piotr, Chien, Yu-Chun, Chang, Yuan-Chih, Wu, Kuen-Phon, Khoo, Kay-Hooi, Chang, Hui-Wen, Hsu, Shang-Te Danny
Format: Article
Language:English
Subjects:
Biological Sciences
Coronaviridae
Coronavirus, Feline - chemistry
Coronaviruses
Cryoelectron Microscopy
Feline infectious peritonitis
Galectins - chemistry
Glycosylation
HEK293 Cells
Humans
Mannose
Mannose - chemistry
Mass spectrometry
Mass spectroscopy
N-glycans
Pathogenesis
Peritonitis
PNAS Plus
Polysaccharides
Protein Conformation
Protein structure
Proteins
Spike Glycoprotein, Coronavirus - chemistry
Spike protein
Viruses
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Summary:Feline infectious peritonitis virus (FIPV) is an alphacoronavirus that causes a nearly 100% mortality rate without effective treatment. Here we report a 3.3-Å cryoelectron microscopy (cryo-EM) structure of the serotype I FIPV spike (S) protein, which is responsible for host recognition and viral entry. Mass spectrometry provided site-specific compositions of densely distributed high-mannose and complex-type N-glycans that account for 1/4 of the total molecular mass; most of the N-glycans could be visualized by cryo-EM. Specifically, the N-glycans that wedge between 2 galectin-like domains within the S1 subunit of FIPV S protein result in a unique propeller-like conformation, underscoring the importance of glycosylation in maintaining protein structures. The cleavage site within the S2 subunit responsible for activation also showed distinct structural features and glycosylation. These structural insights provide a blueprint for a better molecular understanding of the pathogenesis of FIP.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1908898117