A structural analysis of M protein in coronavirus assembly and morphology

• Published in: Journal of structural biology Vol. 174; no. 1; pp. 11 - 22
• Main Authors: Neuman, Benjamin W., Kiss, Gabriella, Kunding, Andreas H., Bhella, David, Baksh, M. Fazil, Connelly, Stephen, Droese, Ben, Klaus, Joseph P., Makino, Shinji, Sawicki, Stanley G., Siddell, Stuart G., Stamou, Dimitrios G., Wilson, Ian A., Kuhn, Peter, Buchmeier, Michael J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2011
• Subjects: Cell Line; Coronavirus; Coronavirus - metabolism; Coronavirus - ultrastructure; Coronavirus M Proteins; Cryo-electron microscopy; Cryo-electron tomography; Cryoelectron Microscopy; Electron Microscope Tomography; Humans; Pleomorphic virus structure; Viral matrix protein; Viral Matrix Proteins - ultrastructure; Virus Assembly - physiology; Virus Assembly - radiation effects; Viral matrix protein; Cryo-electron tomography; Coronavirus; Pleomorphic virus structure; Cryo-electron microscopy
• ISSN: 1047-8477; 1095-8657; 1095-8657
• DOI: 10.1016/j.jsb.2010.11.021

The M protein of coronavirus plays a central role in virus assembly, turning cellular membranes into workshops where virus and host factors come together to make new virus particles. We investigated how M structure and organization is related to virus shape and size using cryo-electron microscopy, tomography and statistical analysis. We present evidence that suggests M can adopt two conformations and that membrane curvature is regulated by one M conformer. Elongated M protein is associated with rigidity, clusters of spikes and a relatively narrow range of membrane curvature. In contrast, compact M protein is associated with flexibility and low spike density. Analysis of several types of virus-like particles and virions revealed that S protein, N protein and genomic RNA each help to regulate virion size and variation, presumably through interactions with M. These findings provide insight into how M protein functions to promote virus assembly.