Baculovirus VP80 Protein and the F-Actin Cytoskeleton Interact and Connect the Viral Replication Factory with the Nuclear Periphery

Marek, Martin; Merten, Otto‐Wilhelm; Galibert, Lionel; Vlak, Just M.; Oers, Monique M. van

doi:10.1128/jvi.00035-11

Cited by 57 publications

(84 citation statements)

References 62 publications

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“…Since the interaction between 38K and VP1054 has been demonstrated previously (35) and since PP78/83 does not locate in the nucleus without BV/ ODV-C42 (31), in the present study we investigated primarily whether VP1054 interacts with BV/ODV-C42 or VP39. In addition, VP80 is a nuclear F-actin-related capsid protein that is required for transport of mature nucleocapsids (55), and both VP80 and VP1054 were proved to interact with 38K (35). So we also investigated whether VP1054 interacts with VP80.…”

Section: Resultsmentioning

confidence: 99%

The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly

Guan

Zhong

et al. 2016

J Virol

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Baculovirus DNAs are synthesized and inserted into preformed capsids to form nucleocapsids at a site in the infected cell nucleus, termed the virogenic stroma. Nucleocapsid assembly of Autographa californica multiple nucleopolyhedrovirus (AcMNPV) requires the major capsid protein VP39 and nine minor capsid proteins, including VP1054. However, how VP1054 participates in nucleocapsid assembly remains elusive. In this study, the VP1054-encoding gene (ac54) was deleted to generate the ac54-knockout AcMNPV (vAc54KO). In vAc54KO-transfected cells, nucleocapsid assembly was disrupted, leading to the formation of abnormally elongated capsid structures. Interestingly, unlike cells transfected with AcMNPV mutants lacking other minor capsid proteins, in which capsid structures were distributed within the virogenic stroma, ac54 ablation resulted in a distinctive location of capsid structures and VP39 at the periphery of the nucleus. The altered distribution pattern of capsid structures was also observed in cells transfected with AcMNPV lacking BV/ODV-C42 or in cytochalasin D-treated AcMNPV-infected cells. BV/ODV-C42, along with PP78/83, has been shown to promote nuclear filamentous actin (F-actin) formation, which is another requisite for nucleocapsid assembly. Immunofluorescence using phalloidin indicated that the formation and distribution of nuclear F-actin were not affected by ac54 deletion. However, immunoelectron microscopy revealed that BV/ODV-C42, PP78/83, and 38K failed to integrate into capsid structures in the absence of VP1054, and immunoprecipitation further demonstrated that in transient expression assays, VP1054 interacted with BV/ODV-C42 and VP80 but not VP39. Our findings suggest that VP1054 plays an important role in the transport of capsid proteins to the nucleocapsid assembly site prior to the process of nucleocapsid assembly. IMPORTANCEBaculoviruses are large DNA viruses whose replication occurs within the host nucleus. The localization of capsids into the capsid assembly site requires virus-induced nuclear F-actin; the inhibition of nuclear F-actin formation results in the retention of capsid structures at the periphery of the nucleus. In this paper, we note that the minor capsid protein VP1054 is essential for the localization of capsid structures, the major capsid protein VP39, and the minor capsid protein 38K into the capsid assembly site. Moreover, VP1054 is crucial for correct targeting of the nuclear F-actin factors BV/ODV-C42 and PP78/83 for capsid maturation. However, the formation and distribution of nuclear F-actin are not affected by the lack of VP1054. We further reveal that VP1054 interacts with BV/ODV-C42 and a capsid transport-related protein, VP80. Taken together, our findings suggest that VP1054 plays a unique role in the pathway(s) for transport of capsid proteins. The family Baculoviridae includes a diverse group of insect-specific viruses that contain circular double-stranded DNA within a rod-shaped protein capsid enclosed by a lipid envelope (1, 2). Two forms of virions (bu...

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Section: Resultsmentioning

confidence: 99%

The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly

Guan

Zhong

et al. 2016

J Virol

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“…During the early stages of infection, a virusinduced specific nuclear region appears, the VS, which is thought to be the active site for viral DNA replication, condensation and packaging into capsids (Fraser, 1986). The newly formed nucleocapsids are transported from the VS to the ring zone region periphery of the inner nuclear membrane and then egress from the nucleus to form BVs in the early stage of infection, or acquire envelopes from intranuclear microvesicles to form ODVs in the late stage of infection (Marek et al, 2011). In the present study, masses of aberrant capsid structures were observed in vBmP95-De-transfected cells.…”

Section: Discussionmentioning

confidence: 99%

“…It has been proposed that P6.9 (Wang et al, 2010a), VP39 (Thiem & Miller, 1989), VP1054 (Olszewski & Miller, 1997), P78/83 , VLF-1 (Vanarsdall et al, 2006), FP25 (Braunagel et al, 1999(Braunagel et al, , 2001, BV/ODV-C42 (Braunagel et al, 2001), ODV-EC27 , vp80 (Marek et al, 2011), P24 (Wolgamot et al, 1993), AC141 (EXON0; Fang et al, 2007), AC142 (McCarthy et al, 2008) and AC98 (38K; Wu et al, 2008) are associated with BV and ODV nucleocapsids. P95, a homologue of Ac83 of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV), is a virion capsid protein of both BV and ODV and was originally characterized as VP91 in Orgyia pseudotsugata MNPV (OpMNPV; .…”

Section: Introductionmentioning

confidence: 99%

Bombyx mori nucleopolyhedrovirus BmP95 plays an essential role in budded virus production and nucleocapsid assembly

Xiang

Shen

Yang

et al. 2013

Journal of General Virology

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Bombyx mori nucleopolyhedrovirus (BmNPV) BmP95 is a highly conserved gene that is found in all of the baculovirus genomes sequenced to date and is also found in nudiviruses. To investigate the role of BmP95 in virus infection in vitro, a BmP95 deletion virus (vBmP95-De) was generated by homologous recombination in Escherichia coli. Fluorescence and light microscopy and titration analysis indicated that the BmP95 deletion bacmid led to a defect in production of infectious budded virus (BV). However, deletion of BmP95 did not affect viral DNA replication. Electron microscopy showed that masses of aberrant tubular structures were present in cells transfected with the BmP95 deletion bacmid, indicating that deletion of BmP95 affected assembly of the nucleocapsid. This defect could be rescued by insertion of full-length BmP95 into the polyhedrin locus of the BmP95-knockout bacmid but not the N-terminal domain of BmP95. Together, these results showed that full-length BmP95 is essential for BV production and is required for nucleocapsid assembly.

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“…On the other hand, the coupling of the DNAbinding function of VP80 to virus morphogenesis has not been established yet. VP80 contains an atypical basic helix-loop-helix (bHLH) DNA-binding domain at its essential C-terminal end (18) and N-terminally located paramyosin-like motifs, likely responsible for the experimentally shown association of VP80 with host nuclear filamentous actin (F-actin) (17). Furthermore, VP80 has been previously shown to interact with 38K, another nucleocapsid-associated protein (19).…”

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confidence: 99%

“…In addition to the above-mentioned VP39, there are a number of minor, but functionally important, capsid-associated proteins (see references 1, 2, and 15 for reviews), which may play essential roles in both recognition of target DNA and its packaging. Among these capsid-associated proteins are two end-linked proteins, very late factor 1 (VLF-1) (16) and VP80 (17,18), which exhibit DNA-binding activities. VLF-1 is a site-specific recombinase and is likely implicated in postreplication processing of viral DNA preceding its packaging (16).…”

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confidence: 99%

Baculovirus VP1054 Is an Acquired Cellular PURα, a Nucleic Acid-Binding Protein Specific for GGN Repeats

Marek

Romier

Galibert

et al. 2013

J Virol

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c Baculovirus VP1054 protein is a structural component of both of the virion types budded virus (BV) and occlusion-derived virus (ODV), but its exact role in virion morphogenesis is poorly defined. In this paper, we reveal sequence and functional similarity between the baculovirus protein VP1054 and the cellular purine-rich element binding protein PUR-alpha (PUR␣). The data strongly suggest that gene transfer has occurred from a host to an ancestral baculovirus. Deletion of the Autographa californica multiple nucleopolyhedrovirus (AcMNPV) vp1054 gene completely prevented viral cell-to-cell spread. Electron microscopy data showed that assembly of progeny nucleocapsids is dramatically reduced in the absence of VP1054. More precisely, VP1054 is required for proper viral DNA encapsidation, as deduced from the formation of numerous electron-lucent capsid-like tubules. Complementary searching identified the presence of genetic elements composed of repeated GGN trinucleotide motifs in baculovirus genomes, the target sequence for PUR␣ proteins. Interestingly, these GGN-rich sequences are disproportionally distributed in baculoviral genomes and mostly occurred in proximity to the gene for the major occlusion body protein polyhedrin. We further demonstrate that the VP1054 protein specifically recognizes these GGN-rich islands, which at the same time encode crucial proline-rich domains in p78/83, an essential gene adjacent to the polyhedrin gene in the AcMNPV genome. While some viruses, like human immunodeficiency virus type 1 (HIV-1) and human JC virus (JCV), utilize host PUR␣ protein, baculoviruses encode the PUR␣-like protein VP1054, which is crucial for viral progeny production.

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Baculovirus VP80 Protein and the F-Actin Cytoskeleton Interact and Connect the Viral Replication Factory with the Nuclear Periphery

Cited by 57 publications

References 62 publications

The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly

The Autographa californica Multiple Nucleopolyhedrovirus ac54 Gene Is Crucial for Localization of the Major Capsid Protein VP39 at the Site of Nucleocapsid Assembly

Bombyx mori nucleopolyhedrovirus BmP95 plays an essential role in budded virus production and nucleocapsid assembly

Baculovirus VP1054 Is an Acquired Cellular PURα, a Nucleic Acid-Binding Protein Specific for GGN Repeats

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