The herpes simplex virus immediate-early ubiquitin ligase ICP0 induces degradation of the ICP0 repressor protein E2FBP1.

E2FBP1/hDRIL1, a DNA-binding A/T-rich interaction domain (ARID) family transcription factor, is expressed ubiquitously in human tissues and plays an essential role in maintaining the proliferation potential of passage-limited human fibroblasts by dissociating promyelocytic leukemia nuclear bodies (PML-NBs). This effect on PML-NBs is similar to that of viral immediate-early gene products, such as infected cellular protein 0 (ICP0) from human herpes simplex virus 1 (HSV-1), which also disrupts PML-NBs to override the intrinsic cellular defense. Here we report that E2FBP1 inhibits accumulation of ICP0 RNA and, at the same time, is degraded via ICP0's herpes ubiquitin ligase 2 (HUL-2) activity upon HSV-1 infection.

Hyperphosphorylation of histone deacetylase 2 by alphaherpesvirus US3 kinases.

A serine/threonine (S/T) kinase encoded by the US3 gene of herpes simplex virus type 1 (HSV-1) is conserved in varicella-zoster virus (VZV) and pseudorabies virus (PRV). Expression of US3 kinase in cells transformed with US3 expression plasmids or infected with each virus results in hyperphosphorylation of histone deacetylase 2 (HDAC2). Mapping studies revealed that each US3 kinase phosphorylates HDAC2 at the same unique conserved Ser residue in its C terminus.

The RING finger domain of Varicella-Zoster virus ORF61p has E3 ubiquitin ligase activity that is essential for efficient autoubiquitination and dispersion of Sp100-containing nuclear bodies.

Varicella zoster virus encodes an immediate-early (IE) protein termed ORF61p that is orthologous to the herpes simplex virus IE protein ICP0. Although these proteins share several functional properties, ORF61p does not fully substitute for ICP0. The greatest region of similarity between these proteins is a RING finger domain.

Identification of phosphorylated residues on varicella-zoster virus immediate-early protein ORF63.

Efficient replication of varicella-zoster virus (VZV) in cell culture requires expression of protein encoded by VZV open reading frame 63 (ORF63p). Two-dimensional gel analysis demonstrates that ORF63p is extensively modified. Mass spectroscopy analysis of ORF63p isolated from transiently transfected HEK 293 and stably transfected MeWo cells identified 10 phosphorylated residues.

Histone deacetylases 1 and 2 are phosphorylated at novel sites during varicella-zoster virus infection.

ORF66p, a virion-associated varicella-zoster virus (VZV) protein, is a member of a conserved Alphaherpesvirinae kinase family with homology to herpes simplex virus US3 kinase. Expression of ORF66p in cells infected with VZV or an adenovirus expressing only ORF66p results in hyperphosphorylation of histone deacetylase 1 (HDAC1) and HDAC2. Mapping studies reveal that phosphorylation is at a unique conserved Ser residue in the C terminus of both HDACs.

Complementation of a herpes simplex virus ICP0 null mutant by varicella-zoster virus ORF61p.

The herpes simplex virus (HSV) ICP0 protein acts to overcome intrinsic cellular defenses that repress viral alpha gene expression. In that vein, viruses that have mutations in ICP0's RING finger or are deleted for the gene are sensitive to interferon, as they fail to direct degradation of promyelocytic leukemia protein (PML), a component of host nuclear domain 10s. While varicella-zoster virus is also insensitive to interferon, ORF61p, its ICP0 ortholog, failed to degrade PML.

Chaperone-fusion expression plasmid vectors for improved solubility of recombinant proteins in Escherichia coli.

The enteric bacterium Escherichia coli is the most extensively used prokaryotic organism for production of proteins of therapeutic or commercial interest. However, it is common that heterologous over-expressed recombinant proteins fail to properly fold resulting in formation of insoluble aggregates known as inclusion bodies. Complex systems have been developed that employ simultaneous over-expression of chaperone proteins to aid proper folding and solubility during bacterial expression.

Components of nuclear domain 10 bodies regulate varicella-zoster virus replication.

PML, Sp100, and Daxx are proteins that normally reside within nuclear domains 10 (ND10s). They associate with DNA virus genomes and repress the very early stages of the DNA virus replication cycle. Virus-encoded proteins counteract this innate antiviral response.

The co-chaperone BAG3 regulates Herpes Simplex Virus replication.

Viruses as obligate intracellular parasites use host cell proteins to ensure efficient replication and spread. Cellular proteins are required for several stages of a virus life cycle. Here, we identify BAG3, a co-chaperone, as a regulator of herpes virus immediate early gene expression.

Nuclear import of the varicella-zoster virus latency-associated protein ORF63 in primary neurons requires expression of the lytic protein ORF61 and occurs in a proteasome-dependent manner.

Varicella-zoster virus (VZV) open reading frame (ORF) 63 protein (ORF63p) is one of six VZV ORFs shown to be transcribed and translated in latently infected human dorsal root ganglia. ORF63p accumulates exclusively in the cytoplasm of latently infected sensory neurons, whereas it is both nuclear and cytoplasmic during lytic infection and following reactivation from latency. Here, we demonstrate that infection of primary guinea pig enteric neurons (EN) with an adenovirus expressing ORF63p results in the exclusive cytoplasmic localization of the protein reminiscent of its distribution during latent VZV infection in humans.

BAG3, a host cochaperone, facilitates varicella-zoster virus replication.

Varicella-zoster virus (VZV) establishes a lifelong latent infection in the dorsal root ganglia of the host. During latency, a subset of virus-encoded regulatory proteins is detected; however, they are excluded from the nucleus. ORF29p, a single-stranded DNA binding protein, is one of these latency-associated proteins.

PATJ, a tight junction-associated PDZ protein, is a novel degradation target of high-risk human papillomavirus E6 and the alternatively spliced isoform 18 E6.

The E6 protein from high-risk human papillomavirus types interacts with and degrades several PDZ domain-containing proteins that localize to adherens junctions or tight junctions in polarized epithelial cells. We have identified the tight junction-associated multi-PDZ protein PATJ (PALS1-associated TJ protein) as a novel binding partner and degradation target of high-risk types 16 and 18 E6. PATJ functions in the assembly of the evolutionarily conserved CRB-PALS1-PATJ and Par6-aPKC-Par3 complexes and is critical for the formation of tight junctions in polarized cells.

Posttranslational modification and cell type-specific degradation of varicella-zoster virus ORF29p.

The ORF29 gene of varicella-zoster virus encodes a single-stranded DNA binding protein that is predominantly nuclear during lytic infection but appears to be restricted to the cytoplasm of latently infected neurons. Following reactivation, ORF29p accumulates in the nuclei of neurons, suggesting that its confinement to the cytosol may be critical for maintaining quiescence. When autonomously expressed, ORF29p accumulates in the nuclei of fibroblasts and the cytoplasm of cells (guinea pig enteric neurons) and cell lines (U373MG) of neuronal origin.

The cellular localization pattern of Varicella-Zoster virus ORF29p is influenced by proteasome-mediated degradation.

Varicella-zoster virus (VZV) open reading frame 29 (ORF29) encodes a single-stranded DNA binding protein. During lytic infection, ORF29p is localized primarily to infected-cell nuclei, whereas during latency it appears in the cytoplasm of infected neurons. Following reactivation, ORF29p accumulates in the nucleus.

Dissection of a novel nuclear localization signal in open reading frame 29 of varicella-zoster virus.

Open reading frame 29 (ORF29) of varicella-zoster virus (VZV) encodes a 120-kDa single-stranded DNA binding protein (ORF29p) that is not packaged in the virion and is expressed during latency. During lytic infection, ORF29p is localized primarily to infected cell nuclei. In contrast, ORF29p is found exclusively in the cytoplasm in neurons of the dorsal root ganglia obtained at autopsy from seropositive latently infected patients.

An early regulatory function required in a cell type-dependent manner is expressed by the genomic but not the cDNA copy of the herpes simplex virus 1 gene encoding infected cell protein 0.

The alpha 0 genes of herpes simplex virus 1 (HSV-1) contain three exons. Earlier studies have shown that the substitution of genomic sequences with a cDNA copy does not alter the capacity of the virus to replicate or establish latent infection. Other studies have demonstrated that HSV-1 may express alternatively spliced forms of alpha 0 transcripts.

The Epstein-Barr virus SM protein is functionally similar to ICP27 from herpes simplex virus in viral infections.

The herpes simplex virus type 1 (HSV-1) ICP27 protein is an essential RNA-binding protein that shuttles between the nucleus and cytoplasm to increase the cytoplasmic accumulation of viral late mRNAs. ICP27 homologs have been identified in each of the herpesvirus subfamilies, and accumulating evidence indicates that homologs from the gammaherpesvirus subfamily function similarly to ICP27. In particular, the Epstein-Barr virus (EBV) SM protein posttranscriptionally regulates gene expression, binds RNA in vitro and in vivo, and shuttles between the nucleus and cytoplasm.