Bacteriophage MS2 displays unreported capsid variability assembling T = 4 and mixed capsids |
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| Authors: | Natàlia de Martín Garrido Michael A Crone Kailash Ramlaul Paul A Simpson Paul S Freemont Christopher H S Aylett |
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| Institution: | 1. Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, SW7 2AZ UK;2. Centre for Structural Biology, Department of Life Sciences, Imperial College London, London, SW7 2AZ UK |
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| Abstract: | Bacteriophage MS2 is a positive-sense, single-stranded RNA virus encapsulated in an asymmetric T = 3 pseudo-icosahedral capsid. It infects Escherichia coli through the F-pilus, in which it binds through a maturation protein incorporated into its capsid. Cryogenic electron microscopy has previously shown that its genome is highly ordered within virions, and that it regulates the assembly process of the capsid. In this study, we have assembled recombinant MS2 capsids with non-genomic RNA containing the capsid incorporation sequence, and investigated the structures formed, revealing that T = 3, T = 4 and mixed capsids between these two triangulation numbers are generated, and resolving structures of T = 3 and T = 4 capsids to 4 Å and 6 Å respectively. We conclude that the basic MS2 capsid can form a mix of T = 3 and T = 4 structures, supporting a role for the ordered genome in favouring the formation of functional T = 3 virions. |
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