8pzp
Model for influenza A virus helical ribonucleoprotein-like structure
Structural highlights
FunctionA0A2Z5UJ33_9INFA Encapsidates the negative strand viral RNA, protecting it from nucleases. The encapsidated genomic RNA is termed the ribonucleoprotein (RNP) and serves as template for transcription and replication. The RNP needs to be localized in the host nucleus to start an infectious cycle, but is too large to diffuse through the nuclear pore complex. NP comprises at least 2 nuclear localization signals that are responsible for the active RNP import into the nucleus through cellular importin alpha/beta pathway. Later in the infection, nclear export of RNPs are mediated through viral proteins NEP interacting with M1 which binds nucleoproteins. It is possible that nucleoprotein binds directly host exportin-1/XPO1 and plays an active role in RNPs nuclear export. M1 interaction with RNP seems to hide nucleoprotein's nuclear localization signals. Soon after a virion infects a new cell, M1 dissociates from the RNP under acidification of the virion driven by M2 protein. Dissociation of M1 from RNP unmasks nucleoprotein's nuclear localization signals, targeting the RNP to the nucleus.[HAMAP-Rule:MF_04070] Publication Abstract from PubMedInfluenza virus genome encapsidation is essential for the formation of a helical viral ribonucleoprotein (vRNP) complex composed of nucleoproteins (NP), the trimeric polymerase, and the viral genome. Although low-resolution vRNP structures are available, it remains unclear how the viral RNA is encapsidated and how NPs assemble into the helical filament specific of influenza vRNPs. In this study, we established a biological tool, the RNP-like particles assembled from recombinant influenza A virus NP and synthetic RNA, and we present the first subnanometric cryo-electron microscopy structure of the helical NP-RNA complex (8.7 to 5.3 A). The helical RNP-like structure reveals a parallel double-stranded conformation, allowing the visualization of NP-NP and NP-RNA interactions. The RNA, located at the interface of neighboring NP protomers, interacts with conserved residues previously described as essential for the NP-RNA interaction. The NP undergoes conformational changes to enable RNA binding and helix formation. Together, our findings provide relevant insights for understanding the mechanism for influenza genome encapsidation. Cryo-EM structure of influenza helical nucleocapsid reveals NP-NP and NP-RNA interactions as a model for the genome encapsidation.,Chenavier F, Estrozi LF, Teulon JM, Zarkadas E, Freslon LL, Pellequer JL, Ruigrok RWH, Schoehn G, Ballandras-Colas A, Crepin T Sci Adv. 2023 Dec 15;9(50):eadj9974. doi: 10.1126/sciadv.adj9974. Epub 2023 Dec , 15. PMID:38100595[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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