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Assembly intermediates of orthoreovirus captured in the cell
Structural highlights
FunctionLMBD1_REOVL Inner capsid (core) component. Displays NTPase, RNA 5'-triphosphatase (RTPase) and RNA helicase activities and probably participates in transcription of the viral genome. Helicase activity might be involved in unwinding or reannealing dsRNA during RNA synthesis. RTPase enzymatic activity represents the first step in RNA capping, which yields a 5'-diphosphorylated plus-strand RNA (By similarity). Publication Abstract from PubMedTraditionally, molecular assembly pathways for viruses are inferred from high resolution structures of purified stable intermediates, low resolution images of cell sections and genetic approaches. Here, we directly visualise an unsuspected 'single shelled' intermediate for a mammalian orthoreovirus in cryo-preserved infected cells, by cryo-electron tomography of cellular lamellae. Particle classification and averaging yields structures to 5.6 A resolution, sufficient to identify secondary structural elements and produce an atomic model of the intermediate, comprising 120 copies each of protein lambda1 and sigma2. This lambda1 shell is 'collapsed' compared to the mature virions, with molecules pushed inwards at the icosahedral fivefolds by ~100 A, reminiscent of the first assembly intermediate of certain prokaryotic dsRNA viruses. This supports the supposition that these viruses share a common ancestor, and suggests mechanisms for the assembly of viruses of the Reoviridae. Such methodology holds promise for dissecting the replication cycle of many viruses. Assembly intermediates of orthoreovirus captured in the cell.,Sutton G, Sun D, Fu X, Kotecha A, Hecksel CW, Clare DK, Zhang P, Stuart DI, Boyce M Nat Commun. 2020 Sep 7;11(1):4445. doi: 10.1038/s41467-020-18243-9. PMID:32895380[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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