Nuclear Transport of Trimeric Assembly Intermediates Exerts a Morphogenetic Control on the Icosahedral Parvovirus Capsid

Riolobos, Laura; Reguera, Juan; Mateu, Mauricio G.; Almendral, José M.

doi:10.1016/j.jmb.2006.01.019

Cited by 57 publications

(99 citation statements)

References 72 publications

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“…1 for nomenclature) interdigitates with neighboring subunits to create trimers, thus probably providing stability (19,24). The GH loop forms the characteristically raised structures at and around the 3-fold apices of the mammalian parvovirus capsid (1,14,18,30,(33)(34)(35) and a ␤-annulus-type structure in GmDNV (29).…”

Section: Vol 85 2011mentioning

confidence: 99%

Structure of Bombyx mori Densovirus 1, a Silkworm Pathogen

Kaufmann

El-Far

Plevka

et al. 2011

J Virol

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Bombyx mori densovirus 1 (BmDNV-1), a major pathogen of silkworms, causes significant losses to the silk industry. The structure of the recombinant BmDNV-1 virus-like particle has been determined at 3.1-Å resolution using X-ray crystallography. It is the first near-atomic-resolution structure of a virus-like particle within the genus Iteravirus. The particles consist of 60 copies of the 55-kDa VP3 coat protein. The capsid protein has a ␤-barrel "jelly roll" fold similar to that found in many diverse icosahedral viruses, including archaeal, bacterial, plant, and animal viruses, as well as other parvoviruses. Most of the surface loops have little structural resemblance to other known parvovirus capsid proteins. In contrast to vertebrate parvoviruses, the N-terminal ␤-strand of BmDNV-1 VP3 is positioned relative to the neighboring 2-fold related subunit in a "domain-swapped" conformation, similar to findings for other invertebrate parvoviruses, suggesting domain swapping is an evolutionarily conserved structural feature of the Densovirinae.Parvoviruses are among the smallest viral pathogens. They form nonenveloped icosahedral particles with a maximum diameter of about 280 Å and have single-stranded DNA genomes. The parvovirus family has been divided into two subfamilies, the Parvovirinae, which infect vertebrates, and the Densovirinae, which infect invertebrates. Bombyx mori densovirus 1 (BmDNV-1) belongs to the Densovirinae subfamily (genus Iteravirus) (17) and causes potentially lethal flacherie disease in silkworms (28), thereby posing a major threat to silk production. So far, only CeDNV (from Casphalia extranea), DpDNV (from Dendrolimus punctatus), and BmDNV-1 belong to the genus Iteravirus, whereas BmDNV-2 and -3 have a bipartite genome with a total length of about 12.5 kb and have been excluded from the Parvoviridae and reassigned to a new family (Bidnaviridae) (31).The 5.1-kb genome of BmDNV-1 has two overlapping genes for the nonstructural proteins in its 5Ј half and a single open reading frame (ORF) that encodes the structural viral proteins (VPs) in the 3Ј portion (17). The VPs are translated using probably four of five initiator codons in the ORF by a leaky scanning mechanism, resulting in four coat protein variants (VP1, 74.9 kb; VP2, 64.3 kb; major capsid protein VP3, 54.9 kb; and VP4, 51.6 kb) (17). The N-terminal part of the largest capsid protein, VP1, contains phospholipase A2 activity that is required for successful infection (7,10,11,17,36). Parvoviruses form Tϭ1 icosahedral capsids that are assembled out of 60 nearly identical VP subunits. Each subunit consists of an eight-stranded antiparallel ␤-barrel known as a "jelly roll" fold (1,13,14,18,29,30,(33)(34)(35). The same fold is utilized by the major capsid protein of many other viruses, ranging from archaeal to bacterial, plant, and animal viruses (4, 20, 27). However, parvoviruses have large insertions in loops connecting the ␤-strands (1,13,14,18,29,30,(33)(34)(35). These insertions define the external surface of the virus, creating feature...

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Section: Vol 85 2011mentioning

confidence: 99%

Structure of Bombyx mori Densovirus 1, a Silkworm Pathogen

Kaufmann

El-Far

Plevka

et al. 2011

J Virol

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“…In early steps, incoming capsids need to either enter the nucleus or at least dock to the nuclear membrane to inject the viral genome into the nucleus (18)(19)(20)(21). In late steps of infection, newly synthesized capsid proteins rapidly assemble into trimers before nuclear transport (22,23). In the nucleus, trimers assemble into capsids prior to DNA packaging and export of complete viruses from the cell (24).…”

mentioning

confidence: 99%

“…In the nucleus, trimers assemble into capsids prior to DNA packaging and export of complete viruses from the cell (24). The ratio of VP1 and VP2 proteins in the capsid varies between 1:5 and 1:10, and therefore trimers contain either three copies of VP2 or two copies of VP2 with one copy of VP1 (23,25). Nuclear transport of a small protein (Ͻ50 kDa) can be achieved by slow, passive diffusion through the nuclear pore complex (26).…”

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confidence: 99%

Classic Nuclear Localization Signals and a Novel Nuclear Localization Motif Are Required for Nuclear Transport of Porcine Parvovirus Capsid Proteins

Boisvert

Bouchard-Lévesque

Fernandes

et al. 2014

J Virol

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Nuclear targeting of capsid proteins (VPs) is important for genome delivery and precedes assembly in the replication cycle of porcine parvovirus (PPV). Clusters of basic amino acids, corresponding to potential nuclear localization signals (NLS), were found only in the unique region of VP1 (VP1up, for VP1 unique part). Of the five identified basic regions (BR), three were important for nuclear localization of VP1up: BR1 was a classic Pat7 NLS, and the combination of BR4 and BR5 was a classic bipartite NLS. These NLS were essential for viral replication. VP2, the major capsid protein, lacked these NLS and contained no region with more than two basic amino acids in proximity. However, three regions of basic clusters were identified in the folded protein, assembled into a trimeric structure. Mutagenesis experiments showed that only one of these three regions was involved in VP2 transport to the nucleus. This structural NLS, termed the nuclear localization motif (NLM), is located inside the assembled capsid and thus can be used to transport trimers to the nucleus in late steps of infection but not for virions in initial infection steps. The two NLS of VP1up are located in the N-terminal part of the protein, externalized from the capsid during endosomal transit, exposing them for nuclear targeting during early steps of infection. Globally, the determinants of nuclear transport of structural proteins of PPV were different from those of closely related parvoviruses. IMPORTANCEMost DNA viruses use the nucleus for their replication cycle. Thus, structural proteins need to be targeted to this cellular compartment at two distinct steps of the infection: in early steps to deliver viral genomes to the nucleus and in late steps to assemble new viruses. Nuclear targeting of proteins depends on the recognition of a stretch of basic amino acids by cellular transport proteins. This study reports the identification of two classic nuclear localization signals in the minor capsid protein (VP1) of porcine parvovirus. The major protein (VP2) nuclear localization was shown to depend on a complex structural motif. This motif can be used as a strategy by the virus to avoid transport of incorrectly folded proteins and to selectively import assembled trimers into the nucleus. Structural nuclear localization motifs can also be important for nuclear proteins without a classic basic amino acid stretch, including multimeric cellular proteins.

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“…This difference could be explained by the possibility that PPV VLPs finish their assembly in the nucleus forming conformational epitopes. Taking into consideration trimer translocation model for other parvoviruses [40], conformational epitopes might be available only in intact capsid but not in trimmers or pentamers formed by VP2 protein. This possibility emphasizes the importance of properly assembled VLPs to elicit strong immune responses when using recombinant antigens as potential vaccines.…”

Section: Generation Of Monoclonal Antibodies and Their Characterizationmentioning

confidence: 99%

Generation of recombinant porcine parvovirus virus-like particles in Saccharomyces cerevisiae and development of virus-specific monoclonal antibodies

Burneikiene

Tamošiūnas

Akatov

et al. 2014

Journal of Biotechnology

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Porcine parvovirus (PPV) is a widespread infectious virus that causes serious reproductive diseases of swine and death of piglets. The gene coding for the major capsid protein VP2 of PPV was amplified using viral nucleic acid extract from swine serum and inserted into yeast Saccharomyces cerevisiae expression plasmid. Recombinant PPV VP2 protein was efficiently expressed in yeast and purified using density gradient centrifugation. Electron microscopy analysis of purified PPV VP2 protein revealed the selfassembly of virus-like particles (VLPs). Nine monoclonal antibodies (MAbs) against the recombinant PPV VP2 protein were generated. The specificity of the newly generated MAbs was proven by immunofluorescence analysis of PPV-infected cells. Indirect IgG ELISA based on the recombinant VLPs for detection of PPV-specific antibodies in swine sera was developed and evaluated. The sensitivity and specificity of the new assay were found to be 93.4% and 97.4%, respectively. In conclusion, yeast S. cerevisiae represents a promising expression system for generating recombinant PPV VP2 protein VLPs of diagnostic relevance.

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Nuclear Transport of Trimeric Assembly Intermediates Exerts a Morphogenetic Control on the Icosahedral Parvovirus Capsid

Cited by 57 publications

References 72 publications

Structure of Bombyx mori Densovirus 1, a Silkworm Pathogen

Structure of Bombyx mori Densovirus 1, a Silkworm Pathogen

Classic Nuclear Localization Signals and a Novel Nuclear Localization Motif Are Required for Nuclear Transport of Porcine Parvovirus Capsid Proteins

Generation of recombinant porcine parvovirus virus-like particles in Saccharomyces cerevisiae and development of virus-specific monoclonal antibodies

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