Structural stabilization of the intrinsically disordered SARS-CoV-2 N by binding to RNA sequences engineered from the viral genome fragment

Abstract The nucleocapsid N is one of four structural proteins of the coronaviruses. Its essential role in genome encapsidation makes it a critical therapeutic target for COVID-19 and related diseases. However, the inherent disorder of full-length N hampers its structural analysis. Here, we describe...

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Main Authors: Sara Landeras-Bueno, Chitra Hariharan, Ruben Diaz Avalos, Andrew S. Norris, Dalton T. Snyder, Kathryn M. Hastie, Stephanie Harkins, Michelle Zandonatti, Roshan R. Rajamanickam, Eduardo Olmedillas, Robyn Miller, Sujan Shresta, Vicki H. Wysocki, Erica Ollmann Saphire
Format: Article
Language:English
Published: Nature Portfolio 2025-07-01
Series:Nature Communications
Online Access:https://doi.org/10.1038/s41467-025-61861-4
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Summary:Abstract The nucleocapsid N is one of four structural proteins of the coronaviruses. Its essential role in genome encapsidation makes it a critical therapeutic target for COVID-19 and related diseases. However, the inherent disorder of full-length N hampers its structural analysis. Here, we describe a stepwise method using viral-derived RNAs to stabilize SARS-CoV-2 N for EM analysis. We identify pieces of RNA from the SARS-CoV-2 genome that promote the formation of structurally homogeneous N dimers, intermediates of assembly, and filamentous capsid-like structures. Building on these results, we engineer a symmetric RNA to stabilize N protein dimers, the building block of high-order assemblies, for EM studies. We combine domain-specific monoclonal antibodies against N with chemical cross-linking mass spectrometry to validate the spatial arrangement of the N domains within the dimer. Additionally, our cryo-EM analysis reveals novel antigenic sites on the N protein. Our findings provide insights into N protein´s architectural and antigenic principles, which can guide design of pan-coronavirus therapeutics.
ISSN:2041-1723