Molecular Biology of Papovaviruses

Fareed, George C.; Davoli, Dana

doi:10.1146/annurev.bi.46.070177.002351

Cited by 121 publications

(61 citation statements)

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“…Such variants were particularly prevalent in plasmids rescued from single colonies grown to mass culture or from cultures of pooled G418-resistant MOP colonies passaged for an extended period of time. These observations are consistent with the hypothesis that variants arise during growth of the virus-infected MOP cells, perhaps through processes similar to that observed when polyomavirus itself is passaged at high multiplicities in permissive cells (11). The fact that all clones (except clone 2) produced at least some intact plasmids as judged by restriction enzyme analysis and functional assay for supF further supports this hypothesis.…”

Section: Resultssupporting

confidence: 86%

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Characterization of a retrovirus shuttle vector capable of either proviral integration or extrachromosomal replication in mouse cells.

Berger¹,

Bernstein²

1985

Mol. Cell. Biol.

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A retrovirus shuttle vector is described that contains the dominant selectable neo gene which confers resistance to kanamycin in bacteria and to the drug G418 in animal cells. The bacterial supF gene and the origins of DNA replication from polyomavirus and the ColE1 replicon also have been included in this vector. Infection of normal rodent cells results in single-copy proviral integration, whereas infection of mouse (MOP) cells expressing polyoma large T antigen results in extrachromosomal replication of the DNA form of the virus. The copy number of the extrachromosomal circles in MOP cells varies from 0 to 100 copies per cell. G418-resistant MOP cells lose their drug-resistant phenotype after passage under nonselective conditions, suggesting that maintenance of the extrachromosomal circles is unstable. The extrachromosomal form of the virus can be recovered as plasmids in Escherichia coli. Two-thirds of the circles analyzed were found to be structurally intact. The others have undergone rearrangements including deletions and insertions. The bacterial supF gene was found to be intact in the majority of recovered plasmids. The data presented here suggest that these retroviruses should be useful as gene transfer vectors for animal cells in culture or in vivo.

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Section: Resultssupporting

confidence: 86%

“…7). We have not extensively analyzed the variants containing insertions, but studies with polyoma mutants generated by passaging at high multiplicity suggest that such variants can contain genomic DNA or Py DNA duplications (11). No variants have been observed which contain deletions in the neo region (region 2).…”

Section: Resultsmentioning

confidence: 99%

Characterization of a retrovirus shuttle vector capable of either proviral integration or extrachromosomal replication in mouse cells.

Berger¹,

Bernstein²

1985

Mol. Cell. Biol.

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“…Many viral pathogens, such as simian virus 40, adenovirus, and white spot syndrome virus, utilize these basic DNA-binding pro-teins (histones or protamines) to maintain their genomes in viral chromatin and/or package their genomes into nucleocapsids (5)(6)(7). The PTM changes in the histone may be involved in the process of viral infection (8).…”

mentioning

confidence: 99%

Posttranslational Modifications of Baculovirus Protamine-Like Protein P6.9 and the Significance of Its Hyperphosphorylation for Viral Very Late Gene Hyperexpression

Zhao

Lai

et al. 2015

J Virol

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Many viruses utilize viral or cellular chromatin machinery for efficient infection. Baculoviruses encode a conserved protaminelike protein, P6.9. This protein plays essential roles in various viral physiological processes during infection. However, the mechanism by which P6.9 regulates transcription remains unknown. In this study, 7 phosphorylated species of P6.9 were resolved in Sf9 cells infected with the baculovirus type species Autographa californica multiple nucleopolyhedrovirus (AcMNPV). Mass spectrometry identified 22 phosphorylation and 10 methylation sites but no acetylation sites in P6.9. Immunofluorescence demonstrated that the P6.9 and virus-encoded serine/threonine kinase PK1 exhibited similar distribution patterns in infected cells, and coimmunoprecipitation confirmed the interaction between them. Upon pk1 deletion, nucleocapsid assembly and polyhedron formation were interrupted and the transcription of viral very late genes was downregulated. Interestingly, we found that the 3 most phosphorylated P6.9 species vanished from Sf9 cells transfected with the pk1 deletion mutant, suggesting that PK1 is involved in the hyperphosphorylation of P6.9. Mass spectrometry suggested that the phosphorylation of the 7 Ser/Thr and 5 Arg residues in P6.9 was PK1 dependent. Replacement of the 7 Ser/Thr residues with Ala resulted in a P6.9 phosphorylation pattern similar to that of the pk1 deletion mutant. Importantly, the decreases in the transcription level of viral very late genes and viral infectivity were consistent. Our findings reveal that P6.9 hyperphosphorylation is a precondition for the maximal hyperexpression of baculovirus very late genes and provide the first experimental insights into the function of the baculovirus protaminelike protein and the related protein kinase in epigenetics. IMPORTANCEDiverse posttranslational modifications (PTMs) of histones constitute a code that creates binding platforms that recruit transcription factors to regulate gene expression. Many viruses also utilize host-or virus-induced chromatin machinery to promote efficient infections. Baculoviruses encode a protamine-like protein, P6.9, which is required for a variety of processes in the infection cycle. Currently, P6.9's PTM sites and its regulating factors remain unknown. Here, we found that P6.9 could be categorized as unphosphorylated, hypophosphorylated, and hyperphosphorylated species and that a virusencoded serine/threonine kinase, PK1, was essential for P6.9 hyperphosphorylation. Abundant PTM sites on P6.9 were identified, among which 7 Ser/Thr phosphorylated sites were PK1 dependent. Mutation of these Ser/Thr sites reduced very late viral gene transcription and viral infectivity, indicating that the PK1-mediated P6.9 hyperphosphorylation contributes to viral proliferation. These data suggest that a code exists in the sophisticated PTM of viral protamine-like proteins and participates in viral gene transcription. In eukaryotic cells, genomic DNA is packaged into nucleosomes, the structural unit of chromatin, b...

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“…and papilloma viruses [l]. In all these viruses a covalently closed circular DNA molecule is associated with histones and encapsidated in an isocahedral structure [2,3]. The two genera diverge on the basis of higher dimensions observed for the papilloma virus capsids (55 nm compared to 40 nm) and for the DNA genome ( M , = 5 x lo6 compared to 3.3 x lo6 [41).…”

mentioning

confidence: 99%

Molecular Cloning, Refined Physical Map and Heterogeneity of Methylation Sites of Papilloma Virus Type 1a DNA

1980

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The entire genome of human papilloma virus type 1a was cloned in Escherichia coli using the plasmid pBR322 as vector. The integrity and the homogeneity of the viral DNA thus obtained was confirmed by restriction endonucleases analysis. Viral DNA isolated from a single wart was partially methylated at only one out of the four HpaII sites, d(C‐C‐G‐G). Recognition sites for BglI, BglII, PstI and PvuII restriction endonucleases were located on the cloned genome.

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Molecular Biology of Papovaviruses

Cited by 121 publications

References 0 publications

Characterization of a retrovirus shuttle vector capable of either proviral integration or extrachromosomal replication in mouse cells.

Characterization of a retrovirus shuttle vector capable of either proviral integration or extrachromosomal replication in mouse cells.

Posttranslational Modifications of Baculovirus Protamine-Like Protein P6.9 and the Significance of Its Hyperphosphorylation for Viral Very Late Gene Hyperexpression

Molecular Cloning, Refined Physical Map and Heterogeneity of Methylation Sites of Papilloma Virus Type 1a DNA

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