5jxs
Mutant GC216/7AA of 3D polymerase from Foot-and-Mouth Disease Virus
Structural highlights
FunctionPOLG_FMDVS 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 PubMedThe Picornaviridae is a large family of positive-sense RNA viruses that contains numerous human and animal pathogens, including foot-and-mouth disease virus (FMDV). The picornavirus replication complex comprises a co-ordinated network of protein-protein and protein-RNA interactions involving multiple viral and host-cellular factors. Many of the proteins within the complex possess multiple roles in viral RNA replication, some of which can be provided in trans (i.e. via expression from a separate RNA molecule), whilst other are required in cis (i.e. expressed from the template RNA molecule). In vitro studies have suggested that multiple copies of the RNA-dependent RNA-polymerase (RdRp), 3D, are involved in the viral replication complex. However, it is not clear whether all these molecules are catalytically active or what other function(s) they provide. In this study, we aimed to distinguish between catalytically-active 3D molecules and those which build a replication complex. We report a novel non-enzymatic cis-acting function of 3D that is essential for viral genome replication. Using a FMDV replicon in complementation experiments, our data demonstrate that this cis-acting role of 3D is distinct from the catalytic activity, which is predominantly trans-acting. Immunofluorescence studies suggest that both cis- and trans-acting 3D molecules localise to the same cellular compartment. However, our genetic and structural data suggest that 3D interacts in cis with RNA stem-loops that are essential for viral RNA replication. Together, this study identifies a previously undescribed aspect of picornavirus replication complex structure-function and an important methodology for probing such interactions further. IMPORTANCE: Foot-and-mouth disease virus (FMDV) is an important animal pathogen responsible for foot-and-mouth disease. The disease is endemic in many parts of the world with outbreaks within livestock resulting in major economic losses. Propagation of the viral genome occurs within replication complexes and understanding this process can facilitate the development of novel therapeutic strategies. Many of the non-structural proteins involved in replication possess multiple functions in the viral life-cycle, some of which can be supplied to the replication complex from a separate genome (i.e. in trans) whilst other must originate from the template (i.e. in cis). Here, we present an analysis of cis- and trans-activities of the RNA-dependent RNA-polymerase, 3D. We demonstrate a novel cis-acting role of 3D in replication. Our data suggest that this role is distinct from its enzymatic functions and requires interaction with the viral genome. Our data furthers the understanding of genome replication of this important pathogen. Both Cis- and Trans- Activities of the Foot-and-Mouth Disease Virus 3D Polymerase are Essential for Viral RNA Replication.,Herod MR, Ferrer-Orta C, Loundras EA, Ward JC, Verdaguer N, Rowlands DJ, Stonehouse NJ J Virol. 2016 May 18. pii: JVI.00469-16. PMID:27194768[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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