The C Terminus of AvrXa10 Can Be Replaced by the Transcriptional Activation Domain of VP16 from the Herpes Simplex Virus

ABSTRACT The herpes simplex virus (HSV) proteins VP16 and ICP0 play key roles in stimulating the onset of the viral lytic cycle. We sought to explore the regulatory links between these proteins by studying the phenotypes of viral mutants in which the activation functions of both were simultaneously inactivated. This analysis unexpectedly revealed that truncation of the C-terminal transcriptional activation domain of VP16 (allele V422) in an ICP0-deficient background almost completely eliminated immediate-early gene expression and virus replication in Vero and HEL cells. The doubly mutant viral genome persisted in a quiescent state for at least 10 days in HEL cells infected at high multiplicity and could be reactivated by superinfection with wild-type HSV. In contrast, the in1814 VP16 mutation produced a markedly less severe phenotype in the same ICP0-deficient background. These data demonstrate that expression of the immediate-early genes requires ICP0 when the C-terminal activation domain of VP16 is deleted and raise the possibility that the in1814 form of VP16 retains a residual ability to stimulate gene expression during virus infection.

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OCA-B is a functional analog of VP16 but targets a separate surface of the Oct-1 POU domain.

Molecular and Cellular Biology ◽

10.1128/mcb.17.12.7295 ◽

1997 ◽

Vol 17 (12) ◽

pp. 7295-7305 ◽

Cited By ~ 29

Author(s):

R Babb ◽

M A Cleary ◽

W Herr

Keyword(s):

Transcription Factor ◽

Herpes Simplex ◽

Transcriptional Activation ◽

Activation Domain ◽

Transcriptional Activation Domain ◽

Pou Domain ◽

Functional Analog ◽

Simplex Virus ◽

Structural Versatility ◽

Binding Structure

OCA-B is a B-cell-specific coregulator of the broadly expressed POU domain transcription factor Oct-1. OCA-B associates with the Oct-1 POU domain, a bipartite DNA-binding structure containing a POU-specific (POU[S]) domain joined by a flexible linker to a POU homeodomain (POU[H]). Here, we show that OCA-B alters the activity of Oct-1 in two ways. It provides a transcriptional activation domain which, unlike Oct-1, activates an mRNA-type promoter effectively, and it stabilizes Oct-1 on the Oct-1-responsive octamer sequence ATGCAAAT. These properties of OCA-B parallel those displayed by the herpes simplex virus Oct-1 coregulator VP16. OCA-B, however, interacts with a different surface of the DNA-bound Oct-1 POU domain, interacting with both the POU(S) and POU(H) domains and the center of the ATGCAAAT octamer sequence. The OCA-B and VP16 interactions with the Oct-1 POU domain are sufficiently different to permit OCA-B and VP16 to bind the Oct-1 POU domain simultaneously. These results emphasize the structural versatility of the Oct-1 POU domain in its interaction with coregulators.

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Faculty Opinions recommendation of Identification of a promoter-specific transcriptional activation domain at the C terminus of the Wnt effector protein T-cell factor 4.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1010954.172908 ◽

2002 ◽

Author(s):

Randall Moon

Keyword(s):

T Cell ◽

Transcriptional Activation ◽

Effector Protein ◽

Activation Domain ◽

Transcriptional Activation Domain ◽

T Cell Factor ◽

C Terminus

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Transcriptional activation by herpes simplex virus type 1 VP16 in vitro and its inhibition by oligopeptides

Molecular and Cellular Biology ◽

10.1128/mcb.14.5.3484-3493.1994 ◽

1994 ◽

Vol 14 (5) ◽

pp. 3484-3493

Author(s):

T J Wu ◽

G Monokian ◽

D F Mark ◽

C R Wobbe

Keyword(s):

Herpes Simplex Virus ◽

Herpes Simplex ◽

Transcriptional Activation ◽

Deletion Mutant ◽

Full Length ◽

Early Gene ◽

Immediate Early ◽

Simplex Virus

VP16 is a herpes simplex virus (HSV)-encoded transcriptional activator protein that is essential for efficient viral replication and as such may be a target for novel therapeutic agents directed against viral gene expression. We have reconstituted transcriptional activation by VP16 in an in vitro system that is dependent on DNA sequences from HSV immediate-early gene promoters and on protein-protein interactions between VP16 and Oct-1 that are required for VP16 activation in vivo. Activation increased synergistically with the number of TAATGARAT elements (the cis-acting element for VP16 activation in vivo) upstream of the core promoter, and mutations of this element that reduce Oct-1 or VP16 DNA binding reduced transactivation in vitro. A VP16 insertion mutant unable to interact with Oct-1 was inactive, but, surprisingly, a deletion mutant lacking the activation domain was approximately 65% as active as the full-length protein. The activation domains of Oct-1 were necessary for activation in reactions containing the VP16 deletion mutant, and they contributed significantly to activation by full-length VP16. Addition of a GA-rich element present in many HSV immediate-early gene enhancers synergistically stimulated VP16-activated transcription. Finally, oligopeptides that are derived from a region of VP16 thought to contact a cellular factor known as HCF (host cell factor) and that inhibit efficient VP16 binding to the TAATGARAT element also specifically inhibited VP16-activated, but not basal, transcription. Amino acid substitutions in one of these peptides identified three residues that are absolutely required for inhibition and presumably for interaction of VP16 with HCF.

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A Domain of Herpes Simplex Virus pUL33 Required To Release Monomeric Viral Genomes from Cleaved Concatemeric DNA

Journal of Virology ◽

10.1128/jvi.00854-17 ◽

2017 ◽

Vol 91 (20) ◽

Cited By ~ 4

Author(s):

Kui Yang ◽

Xiaoqun Dang ◽

Joel D. Baines

Keyword(s):

Amino Acids ◽

Herpes Simplex Virus ◽

Herpes Simplex ◽

Viral Replication ◽

Dna Cleavage ◽

Artificial Chromosome ◽

Viral Dna ◽

Viral Genomes ◽

C Terminus ◽

Simplex Virus

ABSTRACT Monomeric herpesvirus DNA is cleaved from concatemers and inserted into preformed capsids through the actions of the viral terminase. The terminase of herpes simplex virus (HSV) is composed of three subunits encoded by UL15, UL28, and UL33. The UL33-encoded protein (pUL33) interacts with pUL28, but its precise role in the DNA cleavage and packaging reaction is unclear. To investigate the function of pUL33, we generated a panel of recombinant viruses with either deletions or substitutions in the most conserved regions of UL33 using a bacterial artificial chromosome system. Deletion of 11 amino acids (residues 50 to 60 or residues 110 to 120) precluded viral replication, whereas the truncation of the last 10 amino acids from the pUL33 C terminus did not affect viral replication or the interaction of pUL33 with pUL28. Mutations that replaced the lysine at codon 110 and the arginine at codon 111 with alanine codons failed to replicate, and the pUL33 mutant interacted with pUL28 less efficiently. Interestingly, genomic termini of the large (L) and small (S) components were detected readily in cells infected with these mutants, indicating that concatemeric DNA was cleaved efficiently. However, the release of monomeric genomes as assessed by pulsed-field gel electrophoresis was greatly diminished, and DNA-containing capsids were not observed. These results suggest that pUL33 is necessary for one of the two viral DNA cleavage events required to release individual genomes from concatemeric viral DNA. IMPORTANCE This paper shows a role for pUL33 in one of the two DNA cleavage events required to release monomeric genomes from concatemeric viral DNA. This is the first time that such a phenotype has been observed and is the first identification of a function of this protein relevant to DNA packaging other than its interaction with other terminase components.

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