A Molecular Switch in the Capsid Protein Controls the Particle Polymorphism in an Icosahedral Virus

The recombinant coat protein (CP) of Sesbania mosaic virus (SeMV; genus Sobemovirus) was found to self-assemble into capsids encapsidating 23S rRNA and CP mRNA in Escherichia coli. The CP lacking 22 amino acids from the N-terminus assembled into stable T = 3 capsids that appeared similar to SeMV, in...

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Veröffentlicht in:Virology (New York, N.Y.) N.Y.), 2002-01, Vol.292 (2), p.211-223
Hauptverfasser: Lokesh, G.L., Gowri, T.D.S., Satheshkumar, P.S., Murthy, M.R.N., Savithri, H.S.
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Sprache:eng
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Zusammenfassung:The recombinant coat protein (CP) of Sesbania mosaic virus (SeMV; genus Sobemovirus) was found to self-assemble into capsids encapsidating 23S rRNA and CP mRNA in Escherichia coli. The CP lacking 22 amino acids from the N-terminus assembled into stable T = 3 capsids that appeared similar to SeMV, indicating that the N-terminal 22 amino acid residues are dispensable for T = 3 assembly. Two distinct capsids, T = 1 and pseudo T = 2, were observed when the N-terminal 36 amino acids encompassing the arginine-rich motif (N-ARM) were removed. Only T = 1 particles were observed upon deletion of 65 amino acids from the N-terminus, which also included the sequence element for the β-annulus. These results reveal that N-ARM acts as a molecular switch in regulating T = 3 assembly. Formation of stable pseudo T = 2 particles shows that pentamers of AB dimers could nucleate assembly at icosahedral-5-folds. Capsids assembled from the N-terminally truncated proteins also encapsidated 23S rRNA and CP mRNA, suggesting the presence of sites outside the N-terminal 65 residues that may be involved in RNA–protein interactions.
ISSN:0042-6822
1096-0341
DOI:10.1006/viro.2001.1242