8pe4
Capsid structure of the L-A helper virus from native viral communities
Structural highlights
FunctionGAG_SCVLA Capsid protein self-assembles to form an icosahedral capsid with a T=2 symmetry, 40 nm in diameter, and consisting of 60 capsid proteins asymmetric dimers. The capsid encapsulates the genomic dsRNA and the polymerase and remains intact following cell entry to protect the dsRNA from degradation and to prevent unfavorable antiviral responses in the host cell during all the replication cycle of the virus. Nacent transcripts are transcribed within the structural confines of the virion and are extruded into the cytoplasm.[1] [2] Binds and removes 5' cap structures from cellular mRNA. Forms a covalent bond with m7GMP through His-154 of the capsid protein while releasing the mRNA body.[3] [4] Publication Abstract from PubMedThe high abundance of most viruses in infected host cells benefits their structural characterization. However, endogenous viruses are present in low copy numbers and are therefore challenging to investigate. Here, we retrieve cell extracts enriched with an endogenous virus, the yeast L-A virus. The determined cryo-EM structure discloses capsid-stabilizing cation-pi stacking, widespread across viruses and within the Totiviridae, and an interplay of non-covalent interactions from ten distinct capsomere interfaces. The capsid-embedded mRNA decapping active site trench is supported by a constricting movement of two flexible opposite-facing loops. tRNA-loaded polysomes and other biomacromolecules, presumably mRNA, are found in virus proximity within the cell extract. Mature viruses participate in larger viral communities resembling their rare in-cell equivalents in terms of size, composition, and inter-virus distances. Our results collectively describe a 3D-architecture of a viral milieu, opening the door to cell-extract-based high-resolution structural virology. Delineating organizational principles of the endogenous L-A virus by cryo-EM and computational analysis of native cell extracts.,Schmidt L, Tuting C, Kyrilis FL, Hamdi F, Semchonok DA, Hause G, Meister A, Ihling C, Stubbs MT, Sinz A, Kastritis PL Commun Biol. 2024 May 10;7(1):557. doi: 10.1038/s42003-024-06204-7. PMID:38730276[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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