The UL15 protein of herpes simplex virus type 1 is necessary for the localization of the UL28 and UL33 proteins to viral DNA replication centres

Higgs, Martin R.; Preston, Valerie G.; Stow, Nigel D.

doi:10.1099/vir.0.2008/000448-0

Cited by 19 publications

(31 citation statements)

References 26 publications

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“…This suggests that the three homologues diverge, at least to a certain extent, in their functions. As already mentioned, pUL15 has been implicated in protein transport of other lytic proteins, including HSV pUL28 and pUL33, but also in ATP binding (45,46). This protein also contributes to DNA translocation into the capsid and possesses an endonuclease activity (20,22).…”

Section: Discussionmentioning

confidence: 99%

An Epstein-Barr Virus Mutant Produces Immunogenic Defective Particles Devoid of Viral DNA

Pavlova

Feederle

Gärtner

et al. 2013

J Virol

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c Virus-like particles (VLPs) from hepatitis B and human papillomaviruses have been successfully used as preventative vaccines against these infectious agents. These VLPs consist of a self-associating capsid polymer formed from a single structure protein and are devoid of viral DNA. Since virions from herpesviruses consist of a large number of molecules of viral and cellular origin, generating VLPs from a subset of these would be a particularly arduous task. Therefore, we have adopted an alternative strategy that consists of producing DNA-free defective virus particles in a cell line infected by a herpesvirus mutant incapable of packaging DNA. We previously reported that an Epstein-Barr virus (EBV) mutant devoid of the terminal repeats (⌬TR) that act as packaging signals in herpesviruses produces substantial amounts of VLPs and of light particles (LPs). However, ⌬TR virions retained some infectious genomes, and although these mutants had lost their transforming abilities, this poses potential concerns for clinical applications. Therefore, we have constructed a series of mutants that lack proteins involved in maturation and assessed their ability to produce viral DNA-free VLP/LPs. Some of the introduced mutations were deleterious for capsid maturation and virus production. However, deletion of BFLF1/BFRF1A or of BBRF1 resulted in the production of DNA-free VLPs/LPs. The ⌬BFLF1/BFRF1A viruses elicited a potent CD4 ؉ T-cell response that was indistinguishable from the one obtained with wildtype controls. In summary, the defective particles produced by the ⌬BFLF1/BFRF1A mutant fulfill the criteria of efficacy and safety expected from a preventative vaccine.

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Section: Discussionmentioning

confidence: 99%

An Epstein-Barr Virus Mutant Produces Immunogenic Defective Particles Devoid of Viral DNA

Pavlova

Feederle

Gärtner

et al. 2013

J Virol

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“…Baby hamster kidney 21 clone 13 (BHK) cells and Spodoptera frugiperda strain IPLB-21 (Sf) cells were grown as previously described (1). The HSV-1 UL33 null mutant dlUL33 (originally referred to as UL33 Ϫ ) was propagated on the BHK cell-derived complementing cell line A20 (12,15). Following transfection or infection, BHK cells were maintained in Glasgow minimal essential medium containing 5% newborn calf serum, 100 units of penicillin, and 100 g streptomycin per ml (EC5).…”

Section: Methodsmentioning

confidence: 99%

“…Recent evidence suggests that the terminase complex assembles in the cytoplasm and is imported into the nucleus via a mechanism involving a nuclear localization signal within UL15 (35). UL15 is also necessary for the localization of the terminase to nuclear sites of DNA replication and packaging (15). At present, the enzymatic activities necessary for DNA packaging have not been demonstrated for either the complex or individual subunits of the HSV-1 terminase.…”

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confidence: 95%

“…Within the terminase complex, strong interactions have previously been reported between UL15 and UL28 and between UL28 and UL33 (1,7,17,19,34). Evidence also suggests that UL15 and UL33 may be able to interact directly, albeit more weakly than UL28 and UL33 (7,15). Temperature-sensitive (ts) lesions in UL33 or UL15 reduced both the interaction of the thermolabile protein with the other members of the terminase complex and viral growth at the nonpermissive temperature (36).…”

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confidence: 99%

“…No specific role in terminase activity has yet been ascribed to UL33, but several possibilities have been proposed including (i) ensuring correct folding or assembly of the complex, (ii) regulating the functions of the other subunits, (iii) performing an essential enzymatic role per se, and (iv) ensuring correct localization of the terminase to sites of DNA packaging (7). However, recent immunofluorescence studies using mutants with defects in the individual terminase subunits suggest that UL33 is unlikely to be involved in this last function (15).…”

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confidence: 99%

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Mutational Analysis of the Herpes Simplex Virus Type 1 DNA Packaging Protein UL33

Beilstein

Higgs

Stow

2009

J Virol

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The UL33 protein of herpes simplex virus type 1 (HSV-1) is thought to be a component of the terminase complex that mediates the cleavage and packaging of viral DNA. In this study we describe the generation and characterization of a series of 15 UL33 mutants containing insertions of five amino acids located randomly throughout the 130-residue protein. Of these mutants, seven were unable to complement the growth of the UL33-null virus dlUL33 in transient assays and also failed to support the cleavage and packaging of replicated amplicon DNA into capsids. The insertions in these mutants were clustered between residues 51 and 74 and between 104 and 116, within the most highly conserved regions of the protein. The ability of the mutants to interact with the UL28 component of the terminase was assessed in immunoprecipitation and immunofluorescence assays. All four mutants with insertions between amino acids 51 and 74 were impaired in this interaction, whereas two of the three mutants in the second region (with insertions at positions 111 and 116) were not affected. These data indicate that the ability of UL33 to interact with UL28 is probably necessary, but not sufficient, to support viral growth and DNA packaging.During the packaging of the double-stranded DNA genome of herpes simplex virus type 1 (HSV-1), the cleavage of replicated concatemeric viral DNA into single-genome lengths is tightly coupled to its insertion into preassembled spherical procapsids. Upon genome insertion, the internal scaffold protein of the procapsid is lost, and the capsid shell angularizes. Genetic analysis has revealed that successful packaging requires a cis-acting DNA sequence (the a sequence) together with seven proteins, encoded by the UL6, UL15, UL17, UL25, UL28, UL32, and UL33 genes (6, 10). By analogy with doublestranded bacteriophage, the encapsidation of HSV-1 DNA is thought to be mediated by a heteromultimeric terminase enzyme. It is envisaged that the terminase is involved in the recognition of packaging signals present in the concatemers and the association with procapsids via an interaction with the capsid portal protein. Terminase initiates packaging by cleaving at an a sequence present between adjacent genomes within concatemers and subsequently provides energy for genome insertion through the hydrolysis of ATP. Packaging is terminated by a second cleavage event at the next similarly orientated a sequence, resulting in the encapsidation of a unitlength genome.An accumulating body of evidence suggests that the HSV-1 terminase is comprised of the UL15, UL28, and UL33 gene products. Viruses lacking a functional version of any of these three proteins are unable to initiate DNA packaging, and uncleaved concatemers and abortive B-capsids (angularized forms containing scaffold but no DNA) accumulate in the nuclei of infected cells (2,4,5,11,25,27,30,36,38). Protein sequence comparisons revealed a distant relationship between UL15 and the large subunit of bacteriophage T4 terminase, gp17, including the presence of Walker A and B box...

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Herpesvirus Capsid Assembly and DNA Packaging

Heming

Conway

Homa

2017

Advances in Anatomy, Embryology and Cell Biology

130

132

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Herpes simplex virus type I (HSV-1) is the causative agent of several pathologies ranging in severity from the common cold sore to life-threatening encephalitic infection. During productive lytic infection, over 80 viral proteins are expressed in a highly regulated manner, resulting in the replication of viral genomes and assembly of progeny virions. The virion of all herpesviruses consists of an external membrane envelope, a proteinaceous layer called the tegument, and an icosahedral capsid containing the double-stranded linear DNA genome. The capsid shell of HSV-1 is built from four structural proteins: a major capsid protein, VP5, which forms the capsomers (hexons and pentons), the triplex consisting of VP19C and VP23 found between the capsomers, and VP26 which binds to VP5 on hexons but not pentons. In addition, the dodecameric pUL6 portal complex occupies one of the 12 capsid vertices, and the capsid vertex specific component (CVSC), a heterotrimer complex of pUL17, pUL25 and pUL36 binds specifically to the triplexes adjacent to each penton. The capsid is assembled in the nucleus where the viral genome is packaged into newly assembled closed capsid shells. Cleavage and packaging of replicated, concatemeric viral DNA requires the seven viral proteins encoded by the UL6, UL15, UL17, UL25, UL28, UL32, and UL33 genes. Considerable advances have been made in understanding the structure of the herpesvirus capsid and the function of several of the DNA packaging proteins by applying biochemical, genetic, and structural techniques. This review is a summary of recent advances with respect to the structure of the HSV-1 virion capsid and what is known about the function of the seven packaging proteins and their interactions with each other and with the capsid shell.

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The UL15 protein of herpes simplex virus type 1 is necessary for the localization of the UL28 and UL33 proteins to viral DNA replication centres

Cited by 19 publications

References 26 publications

An Epstein-Barr Virus Mutant Produces Immunogenic Defective Particles Devoid of Viral DNA

An Epstein-Barr Virus Mutant Produces Immunogenic Defective Particles Devoid of Viral DNA

Mutational Analysis of the Herpes Simplex Virus Type 1 DNA Packaging Protein UL33

Herpesvirus Capsid Assembly and DNA Packaging

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