29ub | pdb_000029ub
HRV B14 virion
Structural highlights
FunctionPOLG_HRV14 Capsid proteins VP1, VP2, VP3 and VP4 form a closed capsid enclosing the viral positive strand RNA genome. VP4 lies on the inner surface of the protein shell formed by VP1, VP2 and VP3. All the three latter proteins contain a beta-sheet structure called beta-barrel jelly roll. Together they form an icosahedral capsid (T=3) composed of 60 copies of each VP1, VP2, and VP3, with a diameter of approximately 300 Angstroms. VP1 is situated at the 12 fivefold axes, whereas VP2 and VP3 are located at the quasi-sixfold axes (By similarity). The capsid interacts with human ICAM1 to provide virion attachment to target cell. This attachment induces virion internalization predominantly through clathrin- and caveolin-independent endocytosis. VP0 precursor is a component of immature procapsids (By similarity). Protein 2A is a cysteine protease that is responsible for the cleavage between the P1 and P2 regions. It cleaves the host translation initiation factor EIF4G1, in order to shut down the capped cellular mRNA transcription (By similarity). Protein 2B affects membrane integrity and cause an increase in membrane permeability (By similarity). Protein 2C associates with and induces structural rearrangements of intracellular membranes. It displays RNA-binding, nucleotide binding and NTPase activities (By similarity). Protein 3A, via its hydrophobic domain, serves as membrane anchor (By similarity). Protein 3C is a cysteine protease that generates mature viral proteins from the precursor polyprotein. In addition to its proteolytic activity, it binds to viral RNA, and thus influences viral genome replication. RNA and substrate bind co-operatively to the protease (By similarity). RNA-directed RNA polymerase 3D-POL replicates genomic and antigenomic RNA by recognizing replications specific signals (By similarity). Publication Abstract from PubMedHuman rhinoviruses (RV) cause severe socioeconomic problems and are also associated to, or exacerbate, severe respiratory diseases, but no anti-RV drugs are available so far. Understanding the functional role(s) of capsid-RNA interactions in the RV virion may contribute to antiviral drug development. Our previous studies showed that the genome inside the RV-B14 virion is organized as a capsid-bound RNA dodecahedral cage formed by 30 intrachain RNA duplexes; and that positively charged capsid residues close to each RNA duplex, including K4058 and K2052, are involved in viral infection by promoting virion assembly and controlling genome uncoating. In this study, cryogenic electron microscopy was used to investigate the structural basis that underlies the functional roles of those positively charged residues in the RV virion. The atomic structure and equilibrium conformation dynamics of mutant virions carrying either K4058A or K2052A substitutions were compared with those of the parental RV-B14 virion under identical conditions. The results showed that both K4058 and K2052 residues stabilize the RNA duplex structure, and modulate capsid conformation and equilibrium dynamics. Notably, the partially disorganized RNA elements in the K4058A mutant virion strongly resemble those previously found by other researchers in an alternative wild-type RV-B14 structure. Comparison of the two alternative wild-type virion structures and the mutant virion structures supports the existence of two conformational states of the RV virion in the absence of cell receptor: a basal state with well-structured RNA duplexes, and an activated, RNA release-prone state in which the RNA duplexes are partially disorganized. Biologically Relevant, Cationic Residues in Human Rhinovirus Stabilize Capsid-Bound RNA Duplexes, and Restrict Capsid Flexibility.,Martinez-Romero JM, Valiente L, Vilas JL, Riomoros-Barahona V, Valbuena A, Mateu MG, Caston JR J Mol Biol. 2026 Jul 4:169936. doi: 10.1016/j.jmb.2026.169936. PMID:42401367[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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