scholarly journals Herpes Simplex Virus Type 1 ICP0 Phosphorylation Mutants Impair the E3 Ubiquitin Ligase Activity of ICP0 in a Cell Type-Dependent Manner

2008 ◽  
Vol 82 (21) ◽  
pp. 10647-10656 ◽  
Author(s):  
Chris Boutell ◽  
Roger Everett ◽  
Joshua Hilliard ◽  
Priscilla Schaffer ◽  
Anne Orr ◽  
...  
Keyword(s):  
Herpes Simplex ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Transient Transfection ◽  
Dependent Manner ◽  
Cell Type ◽  
Ubiquitin Ligase Activity ◽  
A Cell ◽  
Simplex Virus

ABSTRACT Herpes simplex virus type 1 (HSV-1) infected cell protein 0 (ICP0) is a 110-kDa nuclear phosphoprotein that is required for both the efficient initiation of lytic infection and the reactivation of quiescent viral genomes from latency. The ability of ICP0 to act as a potent viral transactivator is mediated by its N-terminal zinc-binding RING finger domain. This domain confers E3 ubiquitin ligase activity to ICP0 and is required for the proteasome-dependent degradation of a number of cellular proteins during infection, including the major nuclear domain 10 (ND10) constituent protein promyelocytic leukemia. In previous work we mapped three phosphorylation regions within ICP0, two of which directly affected its transactivation capabilities in transient transfection assays (Davido et al., J. Virol. 79:1232-1243, 2005). Because ICP0 is a phosphoprotein, we initially sought to test the hypothesis that phosphorylation regulates the E3 ubiquitin ligase activity of ICP0. Although none of the mutations affected ICP0 E3 ligase activity in vitro, transient transfection analysis indicated that mutations within one or more of the phosphorylated regions impaired the ability of ICP0 to form foci with colocalizing conjugated ubiquitin and to disrupt ND10. Mutations within one of the regions also affected ICP0 stability, and all of these phenomena occurred in a cell type-dependent manner. In the context of viral infection, only one ICP0 phosphorylation mutant (P1) showed a significant defect in viral replication and enhanced protein stability compared to all the other viruses tested. This study suggests that specific cellular environments and context of expression (transfection versus infection) differentially regulate several activities of ICP0 related to its E3 ubiquitin ligase activity via phosphorylation.

scholarly journals Alphaherpesvirus Proteins Related to Herpes Simplex Virus Type 1 ICP0 Induce the Formation of Colocalizing, Conjugated Ubiquitin

2001 ◽  
Vol 75 (11) ◽  
pp. 5357-5362 ◽  
Author(s):  
Jane Parkinson ◽  
Roger D. Everett
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Virus Type ◽  
Ubiquitin Ligase ◽  
Herpes Simplex Virus Type ◽  
E3 Ubiquitin Ligase ◽  
Ring Finger ◽  
Ring Finger Proteins ◽  
Simplex Virus

ABSTRACT Herpes simplex virus type 1 immediate early protein ICP0 influences virus infection by inducing the degradation of specific cellular proteins via a mechanism requiring its RING finger and the ubiquitin-proteasome pathway. Many RING finger proteins, by virtue of their RING finger domain, interact with E2 ubiquitin-conjugating enzymes and act as a component of an E3 ubiquitin ligase. We have recently shown that ICP0 induces the accumulation of colocalizing, conjugated ubiquitin, suggesting that ICP0 can act as or contribute to an E3 ubiquitin ligase. In this report we demonstrate that the ICP0-related RING finger proteins encoded by other alphaherpesviruses also induce colocalizing, conjugated ubiquitin, thereby suggesting that they act by similar biochemical mechanisms.

scholarly journals Herpes Simplex Virus Tegument ICP0 Is Capsid Associated, and Its E3 Ubiquitin Ligase Domain Is Important for Incorporation into Virions

2009 ◽  
Vol 84 (3) ◽  
pp. 1637-1640 ◽  
Author(s):  
Mark G. Delboy ◽  
Carlos R. Siekavizza-Robles ◽  
Anthony V. Nicola
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Ring Finger ◽  
Virion Assembly ◽  
Tegument Proteins ◽  
Ubiquitin Ligase Activity ◽  
Protein Icp0 ◽  
Simplex Virus

ABSTRACT Herpes simplex virus (HSV) immediate-early (IE) protein ICP0 is a multifunctional regulator of HSV infection. ICP0 that is present in the tegument layer has not been well characterized. Protein compositions of wild-type and ICP0 null virions were similar, suggesting that the absence of ICP0 does not grossly impair virion assembly. ICP0 has a RING finger domain with E3 ubiquitin ligase activity that is necessary for IE functions. Virions with mutations in this domain contained greatly reduced levels of tegument ICP0, suggesting that the domain influences the incorporation of ICP0. Virion ICP0 was resistant to removal by detergent and salt and was associated with capsids, features common to inner tegument proteins.

scholarly journals Herpes simplex virus type 1 ICP0 induces CD83 degradation in mature dendritic cells independent of its E3 ubiquitin ligase function

2014 ◽  
Vol 95 (6) ◽  
pp. 1366-1375 ◽  
Author(s):  
Christiane S. Heilingloh ◽  
Petra Mühl-Zürbes ◽  
Alexander Steinkasserer ◽  
Mirko Kummer
Keyword(s):  
Dendritic Cells ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Ubiquitin Ligase ◽  
Herpes Simplex Virus Type ◽  
E3 Ubiquitin Ligase ◽  
Simplex Virus ◽  
Antigen Presenting ◽  
Ligase Function

Mature dendritic cells (mDCs) are the most potent antigen-presenting cells known today, as they are the only antigen-presenting cells able to induce naïve T-cells. Therefore, they play a crucial role during the induction of effective antiviral immune responses. Interestingly, the surface molecule CD83 expressed on mDCs is targeted by several viruses. As CD83 has been shown to exert co-stimulatory functions on mDCs, its downmodulation represents a viral immune escape mechanism. Mechanistically, it has been shown that herpes simplex virus type 1 infection leads to proteasomal degradation of CD83, resulting in a strongly diminished T-cell stimulatory capacity of the infected mDC. Previous data suggest that the viral immediate-early protein ICP0 (infected-cell protein 0) plays an important role in this process. In the present study, we showed that ICP0 is sufficient to induce CD83 degradation in the absence of any other viral factor. However, the mechanism of ICP0-mediated CD83 degradation is not yet understood. Here, we provide evidence that ubiquitination of lysine residues is, despite the published E3 ubiquitin ligase activity of ICP0, not necessary for CD83 degradation. This finding was underlined by the observation that expression of an ICP0 mutant lacking the E3 ubiquitin ligase domain in mDCs still induced CD83 degradation. Finally, inhibition of E1 activating enzyme using the specific inhibitor 4[4-(5-nitro-furan-2-ylmethylene)-3.5-dioxo-pyrazolidin-1-yl]-benzoic acid ethyl ester did not prevent CD83 degradation. Taken together, our data provide strong evidence that ICP0 alone induces CD83 degradation independent of its E3 ubiquitin ligase function and of the ubiquitin machinery.

scholarly journals Discovery of Small-Molecule Inhibitors Targeting the E3 Ubiquitin Ligase Activity of the Herpes Simplex Virus 1 ICP0 Protein Using anIn VitroHigh-Throughput Screening Assay

2019 ◽  
Vol 93 (13) ◽  
Author(s):  
Thibaut Deschamps ◽  
Hope Waisner ◽  
Christos Dogrammatzis ◽  
Anuradha Roy ◽  
Shibin Chacko ◽  
...  
Keyword(s):  
Gene Expression ◽  
Herpes Simplex ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
E3 Ligase ◽  
Screening Assay ◽  
Herpes Simplex Virus 1 ◽  
Ubiquitin Ligase Activity ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACTHerpes simplex virus 1 (HSV-1) has infected more than 80% of the population. Reactivation of the virus causes diseases ranging in severity from benign cold sores to fatal encephalitis. Current treatments involve viral DNA replication inhibitors, but the emergence of drug-resistant mutants is observed frequently, highlighting the need for novel antiviral therapies. Infected cell protein 0 (ICP0) of HSV-1 is encoded by an immediate early gene and plays a fundamental role during infection, because it enables viral gene expression and blocks antiviral responses. One mechanism by which ICP0 functions is through an E3 ubiquitin ligase activity that induces the degradation of targeted proteins. A ΔICP0 virus or mutants with deficiencies in E3 ligase activity cannot counteract beta interferon (IFN-β)-induced restriction of viral infection, are highly immunogenic, are avirulent, and fail to spread. Thus, small molecules interfering with essential and conserved ICP0 functions are expected to compromise HSV-1 infection. We have developed a high-throughput screening assay, based on the autoubiquitination properties of ICP0, to identify small-molecule inhibitors of ICP0 E3 ubiquitin ligase activity. Through a pilot screening procedure, we identified nine compounds that displayed dose-dependent inhibitory effects on ICP0 but not on Mdm2, a control E3 ubiquitin ligase. Following validation, one compound displayed ICP0-dependent inhibition of HSV-1 infection. This compound appeared to bind ICP0 in a cellular thermal shift assay, it blocked ICP0 self-elimination, and it blocked wild-type but not ICP0-null virus gene expression. This scaffold displays specificity and could be used to develop optimized ICP0 E3 ligase inhibitors.IMPORTANCESince acyclovir and its derivatives were launched for herpesviruses control almost four decades ago, the search for novel antivirals has waned. However, as human life expectancy has increased, so has the number of immunocompromised individuals who receive prolonged treatment for HSV recurrences. This has led to an increase in unresponsive patients due to acquired viral drug resistance. Thus, novel treatments need to be explored. Here we explored the HSV-1 ICP0 E3 ligase as a potential antiviral target because (i) ICP0 is expressed before virus replication, (ii) it is essential for infectionin vivo, (iii) it is required for efficient reactivation of the virus from latency, (iv) inhibition of its E3 ligase activity would sustain host immune responses, and (v) it is shared by other herpesviruses. We report a compound that inhibits HSV-1 infection in an ICP0-dependent manner by inhibiting ICP0 E3 ligase activity.

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