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

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.

2000 ◽  
Vol 74 (21) ◽  
pp. 10006-10017 ◽  
Author(s):  
Jane Parkinson ◽  
Roger D. Everett

ABSTRACT The herpes simplex virus type 1 (HSV-1) immediate-early protein ICP0 interacts with several cellular proteins and induces the proteasome-dependent degradation of others during infection. In this study we show that ICP0 is required for the proteasome-dependent degradation of the ND10 protein Sp100 and, as with the other target proteins, the ICP0 RING finger domain is essential. Further, comparison of the kinetics and ICP0 domain requirements for the degradation of PMI and Sp100 suggests that a common mechanism is involved. Homologues of ICP0 are encoded by other members of the alphaherpesvirus family. These proteins show strong sequence homology to ICP0 within the RING finger domain but limited similarity elsewhere. Using transfection assays, we have shown that all the ICP0 homologues that we tested have significant effects on the immunofluorescence staining character of at least one of the proteins destabilized by ICP0, and by using a recombinant virus, we found that the equine herpesvirus ICP0 homologue induced the proteasome-dependent degradation of endogenous CENP-C and modified forms of PML and Sp100. However, in contrast to ICP0, the homologue proteins had no effect on the distribution of the ubiquitin-specific protease USP7 within the cell, consistent with their lack of a USP7 binding domain. We also found that ICP0 by itself could induce the abrogation of SUMO-1 conjugation and then the proteasome-dependent degradation of unmodified exogenous PML in transfected cells, thus demonstrating that other HSV-1 proteins are not required. Surprisingly, the ICP0 homologues were unable to cause these effects. Overall, these data suggest that the members of the ICP0 family of proteins may act via a similar mechanism or pathway involving their RING finger domain but that their intrinsic activities and effects on endogenous and exogenous proteins differ in detail.


2014 ◽  
Vol 95 (6) ◽  
pp. 1366-1375 ◽  
Author(s):  
Christiane S. Heilingloh ◽  
Petra Mühl-Zürbes ◽  
Alexander Steinkasserer ◽  
Mirko Kummer

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.


2002 ◽  
Vol 76 (2) ◽  
pp. 841-850 ◽  
Author(s):  
Chris Boutell ◽  
Seth Sadis ◽  
Roger D. Everett

ABSTRACT Proteasome-dependent degradation of ubiquitinated proteins plays a key role in many important cellular processes. Ubiquitination requires the E1 ubiquitin activating enzyme, an E2 ubiquitin conjugating enzyme, and frequently a substrate-specific ubiquitin protein ligase (E3). One class of E3 ubiquitin ligases has been shown to contain a common zinc-binding RING finger motif. We have previously shown that herpes simplex virus type 1 ICP0, itself a RING finger protein, induces the proteasome-dependent degradation of several cellular proteins and induces the accumulation of colocalizing conjugated ubiquitin in vivo. We now report that both full-length ICP0 and its isolated RING finger domain induce the accumulation of polyubiquitin chains in vitro in the presence of E1 and the E2 enzymes UbcH5a and UbcH6. Mutations within the RING finger region that abolish the in vitro ubiquitination activity also cause severe reductions in ICP0 activity in other assays. We conclude that ICP0 has the potential to act as an E3 ubiquitin ligase during viral infection and to target specific cellular proteins for destruction by the 26S proteasome.


2001 ◽  
Vol 120 (5) ◽  
pp. A136-A137
Author(s):  
K TSAMAKIDES ◽  
E PANOTOPOULOU ◽  
D DIMITROULOPOULOS ◽  
M CHRISTOPOULO ◽  
D XINOPOULOS ◽  
...  

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