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Inside-out FMDV A10 capsid
Structural highlights
FunctionPOLG_FMDV1 The leader protease autocatalytically cleaves itself from the polyprotein at the L/VP0 junction. It cleaves the host translation initiation factors EIF4G1 and EIF4G3, in order to shut down the capped cellular mRNA transcription (By similarity). 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. The capsid interacts with host heparan sulfate and various integrins (alphavbeta1, alphavbeta3, alpha5beta1, alphavbeta6, alphavbeta8) to provide virion attachment to target Attachment via host integrins induces virion internalization predominantly through clathrin-mediated endocytosis (By similarity). Protein VP0: VP0 precursor is a component of immature procapsids (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 3B-1, 3B-2 and 3B-3 are covalently linked to the 5'-end of both the positive-strand and negative-strand genomic RNAs. They acts as a genome-linked replication primer (By similarity). Protease 3C: 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 cooperatively 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 PubMedFoot-and-mouth disease virus (FMDV) belongs to the aphthovirus genus of the Picornaviridae, a family of small, icosahedral, non-enveloped, single-stranded RNA viruses. It is a highly infectious pathogen and is one of the biggest hindrances to the international trade of animals and animal products. FMDV capsids (which are unstable below pH6.5) release their genome into the host cell from an acidic compartment, such as that of an endosome, and in the process dissociate into pentamers. Whilst other members of the family (enteroviruses) have been visualized to form an expanded intermediate capsid with holes from which inner capsid proteins (VP4), N-termini (VP1) and RNA can be released, there has been no visualization of any such state for an aphthovirus, instead the capsid appears to simply dissociate into pentamers. Here we present the 8-A resolution structure of isolated dissociated pentamers of FMDV, lacking VP4. We also found these pentamers to re-associate into a rigid, icosahedrally symmetric assembly, which enabled their structure to be solved at higher resolution (5.2 A). In this assembly, the pentamers unexpectedly associate 'inside out', but still with their exposed hydrophobic edges buried. Stabilizing interactions occur between the HI loop of VP2 and its symmetry related partners at the icosahedral 3-fold axes, and between the BC and EF loops of VP3 with the VP2 betaB-strand and the CD loop at the 2-fold axes. A relatively extensive but subtle structural rearrangement towards the periphery of the dissociated pentamer compared to that in the mature virus provides insight into the mechanism of dissociation of FMDV and the marked difference in antigenicity. Structures of foot and mouth disease virus pentamers: Insight into capsid dissociation and unexpected pentamer reassociation.,Malik N, Kotecha A, Gold S, Asfor A, Ren J, Huiskonen JT, Tuthill TJ, Fry EE, Stuart DI PLoS Pathog. 2017 Sep 22;13(9):e1006607. doi: 10.1371/journal.ppat.1006607. PMID:28937999[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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