Poliovirus subviral particles associated with progeny RNA in the replication complex

Pfister, Thomas D.; Egger, Denise; Bienz, Kurt

doi:10.1099/0022-1317-76-1-63

Cited by 28 publications

(25 citation statements)

References 40 publications

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“…Further evidence for a direct interaction of 2C with capsid proteins was provided by a study in which several mutations in VP1 and VP3 were identified to compensate for a defect in encapsidation [22]. Despite the fact that 2C and capsid precursors (protomeric and pentameric particles) have been shown to co-localize at the surface of replication vesicles and can be cross-linked to viral RNA, it is still unknown whether 2C interacts directly with VP1 or VP3 or with a higher-order assembly intermediate [38], [43]. Our fractionation studies revealed almost exclusively protomers in TP219-treated cells.…”

Section: Discussionmentioning

confidence: 99%

Binding of Glutathione to Enterovirus Capsids Is Essential for Virion Morphogenesis

et al. 2014

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Enteroviruses (family of the Picornaviridae) cover a large group of medically important human pathogens for which no antiviral treatment is approved. Although these viruses have been extensively studied, some aspects of the viral life cycle, in particular morphogenesis, are yet poorly understood. We report the discovery of TP219 as a novel inhibitor of the replication of several enteroviruses, including coxsackievirus and poliovirus. We show that TP219 binds directly glutathione (GSH), thereby rapidly depleting intracellular GSH levels and that this interferes with virus morphogenesis without affecting viral RNA replication. The inhibitory effect on assembly was shown not to depend on an altered reducing environment. Using TP219, we show that GSH is an essential stabilizing cofactor during the transition of protomeric particles into pentameric particles. Sequential passaging of coxsackievirus B3 in the presence of low GSH-levels selected for GSH-independent mutants that harbored a surface-exposed methionine in VP1 at the interface between two protomers. In line with this observation, enteroviruses that already contained this surface-exposed methionine, such as EV71, did not rely on GSH for virus morphogenesis. Biochemical and microscopical analysis provided strong evidence for a direct interaction between GSH and wildtype VP1 and a role for this interaction in localizing assembly intermediates to replication sites. Consistently, the interaction between GSH and mutant VP1 was abolished resulting in a relocalization of the assembly intermediates to replication sites independent from GSH. This study thus reveals GSH as a novel stabilizing host factor essential for the production of infectious enterovirus progeny and provides new insights into the poorly understood process of morphogenesis.

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Section: Discussionmentioning

confidence: 99%

Binding of Glutathione to Enterovirus Capsids Is Essential for Virion Morphogenesis

et al. 2014

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“…There is evidence that 14S subunits, which are pentamers of VP0-VP1-VP3, are the key assembly intermediates in poliovirus assembly. The 14S subunits are always present in infected cells (48), can be chased into mature virions (49,50), and are associated with viral RNA (44,46). Furthermore, in a cell-free system, the 14S subunits can package the viral genome into virions, while procapsids cannot under the same conditions, indicating that the procapsids are either dead end products or a reservoir for the 14S subunits (4,63).…”

Section: Discussionmentioning

confidence: 99%

Requirement of the Adenovirus IVa2 Protein for Virus Assembly

Zhang

Imperiale

2003

J Virol

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The adenovirus L1 52/55-kDa protein is required for viral DNA packaging and interacts with the viral IVa2 protein, which binds to the viral packaging sequence. Previous reports suggest that the IVa2 protein plays a role in viral DNA packaging and that this function of the IVa2 protein is serotype specific. To further examine the function of the IVa2 protein in viral DNA packaging, a mutant virus that does not express the IVa2 protein was constructed by introducing two stop codons at the beginning of the IVa2 open reading frame in a full-length bacterial clone of adenovirus type 5. The mutant virus, pm8002, was defective for growth in 293 cells, although it replicated its DNA and produced early and late viral proteins. Electron microscopic and gradient analyses revealed that the mutant virus did not assemble any viral particles in 293 cells. In 293-IVa2 cells, which express the IVa2 protein, infectious viruses were produced, although the titer of the mutant virus was lower than that of the wild-type virus, indicating that these cells may not fully complement the mutation. The mutant viral particles produced in 293-IVa2 cells were heterogeneous in size and shape, less stable, and did not traffic efficiently to the nucleus. Marker rescue experiments with a wild-type IVa2 DNA fragment confirmed that the only mutations present in pm8002 were in the IVa2 gene. The results indicate that the IVa2 protein is required for adenovirus assembly and suggest that virus particles may be assembled around the DNA rather than DNA being packaged into preformed capsids.The adenovirus capsid is an icosahedron containing three major proteins, hexon (720 molecules/virion), penton base (60 molecules/virion), and fiber (36 molecules/virion) (55, 61, 62), along with a series of minor components. Inside the capsid is the viral genome with associated core proteins (47). During assembly, hexon proteins trimerize to form hexon capsomers, which are the major structural units of the capsid (45). These capsomers then come together with the other capsid proteins and scaffolding proteins to form the capsid. The mechanisms of how adenovirus particles assemble and viral DNA is packaged are not yet fully understood. Empty capsids, which contain no viral DNA or core proteins, are produced in parallel to mature virions in infected cells (57). Intermediate particles with buoyant densities between those of empty capsids and mature virions have also been isolated from infected cells. These intermediates can be divided into light ( ϭ 1.315 g/cm 3 ) particles containing small DNA fragments and heavy ( ϭ 1.37 g/cm 3 ) particles containing full-length DNA (11). Kinetic radiolabeling and pulse-chase studies suggest that these empty capsids and intermediate particles are precursors of mature virions (34,35,57). On the basis of these early studies, it is generally believed that the viral genome and core proteins are inserted into preassembled empty capsids. Studies of the protein composition of empty capsids and intermediate particles also support the precursor-...

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“…Expression of picornavirus protein 2C in mammalian cells results in the formation of vesicles (1,11,59,60). In infected cells, these virus-induced vesicles are tightly associated with the viral replication complexes (7,9), the sites of RNA replication and virus assembly (6,50). Protein 2C, as well as the processing precursor 2BC, are believed to spatially organize the replication complex (6,8).…”

Section: Discussionmentioning

confidence: 99%

Polypeptide p41 of a Norwalk-Like Virus Is a Nucleic Acid-Independent Nucleoside Triphosphatase

Pfister

Wimmer

2001

J Virol

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Southampton virus (SHV) is a member of the Norwalk-like viruses (NLVs), one of four genera of the familyCaliciviridae. The genome of SHV contains three open reading frames (ORFs). ORF 1 encodes a polyprotein that is autocatalytically processed into six proteins, one of which is p41. p41 shares sequence motifs with protein 2C of picornaviruses and superfamily 3 helicases. We have expressed p41 of SHV in bacteria. Purified p41 exhibited nucleoside triphosphate (NTP)-binding and NTP hydrolysis activities. The NTPase activity was not stimulated by single-stranded nucleic acids. SHV p41 had no detectable helicase activity. Protein sequence comparison between the consensus sequences of NLV p41 and enterovirus protein 2C revealed regions of high similarity. According to secondary structure prediction, the conserved regions were located within a putative central domain of alpha helices and beta strands. This study reveals for the first time an NTPase activity associated with a calicivirus-encoded protein. Based on enzymatic properties and sequence information, a functional relationship between NLV p41 and enterovirus 2C is discussed in regard to the role of 2C-like proteins in virus replication.

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Poliovirus subviral particles associated with progeny RNA in the replication complex

Cited by 28 publications

References 40 publications

Binding of Glutathione to Enterovirus Capsids Is Essential for Virion Morphogenesis

Binding of Glutathione to Enterovirus Capsids Is Essential for Virion Morphogenesis

Requirement of the Adenovirus IVa2 Protein for Virus Assembly

Polypeptide p41 of a Norwalk-Like Virus Is a Nucleic Acid-Independent Nucleoside Triphosphatase

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