scholarly journals The Mre11 Cellular Protein Is Modified by Conjugation of Both SUMO-1 and SUMO-2/3 during Adenovirus Infection

ISRN Virology ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Elizabeth Castillo-Villanueva ◽  
Grisel Ballesteros ◽  
Melanie Schmid ◽  
Paloma Hidalgo ◽  
Sabrina Schreiner ◽  
...  
Keyword(s):  
Adenovirus Type ◽  
Cellular Protein ◽  
Cellular Proteins ◽  
Cellular Targets ◽  
Orf3 Protein ◽  
Mrn Complex ◽  
Early Proteins ◽  
Sumo Ligase ◽  
Cullin 5 ◽  
Infected Cells

The adenovirus type 5 (Ad5) E1B 55 kDa and E4 Orf6 proteins assemble a Cullin 5-E3 ubiquitin (Ub) ligase that targets, among other cellular proteins, p53 and the Mre11-Rad50-Nbs1 (MRN) complex for degradation. The latter is also inhibited by the E4 Orf3 protein, which promotes the recruitment of Mre11 into specific nuclear sites to promote viral DNA replication. The activities associated with the E1B 55 kDa and E4 Orf6 viral proteins depend mostly on the assembly of this E3-Ub ligase. However, E1B 55 kDa can also function as an E3-SUMO ligase, suggesting not only that regulation of cellular proteins by these viral early proteins may depend on polyubiquitination and proteasomal degradation but also that SUMOylation of target proteins may play a key role in their activities. Since Mre11 is a target of both the E1B/E4 Orf6 complex and E4 Orf3, we decided to determine whether Mre11 displayed similar properties to those of other cellular targets, in Ad5-infected cells. We have found that during Ad5-infection, Mre11 is modified by SUMO-1 and SUMO-2/3 conjugation. Unexpectedly, SUMOylation of Mre11 is not exclusively dependent on E1B 55 kDa, E4 Orf6, or E4 Orf3, rather it seems to be influenced by a molecular interplay that involves each of these viral early proteins.

scholarly journals Mechanism of Adenovirus E4-ORF3-Mediated SUMO Modifications

mBio ◽  
2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Sook-Young Sohn ◽  
Patrick Hearing
Keyword(s):  
E3 Ligase ◽  
Host Cells ◽  
Cellular Proteins ◽  
Target Proteins ◽  
Orf3 Protein ◽  
Sumo Conjugation ◽  
Sumo Ligase ◽  
Infected Cells ◽  
Sumo E3 Ligase

ABSTRACTRegulation of a variety of different cellular processes, including posttranslational modifications, is critical for the ability of many viruses to replicate efficiently within host cells. The adenovirus (Ad) E4-ORF3 protein assembles into polymers and forms a unique nuclear scaffold that leads to the relocalization and sequestration of cellular proteins, including small ubiquitin-like modifiers (SUMOs). Previously, we showed that E4-ORF3 functions as a SUMO E3 ligase of transcriptional intermediary factor-1 gamma (TIF-1γ) and promotes poly-SUMO chain formation. Here, we present cellular and biochemical data to further understand E4-ORF3 SUMO ligase activity. E4-ORF3 proteins from five different Ad species were found to possess SUMO E3 ligase activitiesin vitro. In infected cells, SUMO modifications of target proteins occurred only when the proteins were recruited into E4-ORF3 polymeric structures. By analyzing SUMO-deficient TIF-1γ, we demonstrated that SUMO conjugations are not required for E4-ORF3-mediated relocalization of target proteins in infected cells, implying that sequestration is followed by SUMO modification.In vitroSUMO conjugation assays revealed the Ad E1B-55K oncoprotein as a new viral target of E4-ORF3-mediated SUMOylation. We also verified a direct function of E4-ORF3 as a SUMO ligase for multiple cellular proteins, including transcription factor II-I (TFII-I), Nbs1, and Mre11. Moreover, we discovered that E4-ORF3 associates with SUMO-bound UBC9, and E4-ORF3 polymerization is crucial for this ternary interaction. Together, our findings characterize E4-ORF3 as a novel polymer-type SUMO E3 ligase and provide mechanistic insights into the role of E4-ORF3 in SUMO conjugation.IMPORTANCEViruses interplay with the host SUMOylation system to manipulate diverse cellular responses. The Ad E4-ORF3 protein forms a dynamic nuclear network to interfere with and exploit different host processes, including the DNA damage and interferon responses. We previously reported that E4-ORF3 is a SUMO E3 ligase. Here, we demonstrate that this activity is a conserved function of evolutionarily diverse human Ad E4-ORF3 proteins and that E4-ORF3 functions directly to promote SUMO conjugations to multiple cellular proteins. Recruitment of cellular substrates into E4-ORF3 nuclear inclusions is required for SUMO conjugation to occurin vivo. We probed the mechanism by which E4-ORF3 functions as a SUMO E3 ligase. Only multimeric, but not dimeric, E4-ORF3 binds to the SUMO E2 conjugation enzyme UBC9in vitroonly in a trimeric complex with SUMO. These results reveal a novel mechanism by which a conserved viral protein usurps the cellular SUMO conjugation machinery.

scholarly journals Adenovirus Ubiquitin-Protein Ligase Stimulates Viral Late mRNA NuclearExport

2007 ◽  
Vol 81 (2) ◽  
pp. 575-587 ◽  
Author(s):  
Jennifer L. Woo ◽  
Arnold J. Berk
Keyword(s):  
Protein Synthesis ◽  
Nuclear Export ◽  
Mrna Export ◽  
Dominant Negative ◽  
Cellular Proteins ◽  
Mutant Form ◽  
Ubiquitin Protein Ligase ◽  
Mrn Complex ◽  
Early Protein ◽  
Cullin 5

ABSTRACT Theadenovirus type 5 (Ad5) E1B-55K and E4orf6 proteins are required together to stimulate viral late nuclear mRNA export to the cytoplasm and to restrict host cell nuclear mRNA export during the late phase of infection. Previous studies have shown that these two viral proteins interact with the cellular proteins elongins B and C, cullin 5, RBX1, and additional cellular proteins to form an E3 ubiquitin-protein ligase that polyubiquitinates p53 and probably one or more subunits of the MRE11-RAD50-NBS1 (MRN) complex, directing their proteasomal degradation. The MRN complex is required for cellular DNA double-strand break repair and induction of the DNA damage response by adenovirus infection. To determine if the ability of E1B-55K and E4orf6 to stimulate viral late mRNA nuclear export requires the ubiquitin-protein ligase activity of this viral ubiquitin-protein ligase complex, we designed and expressed a dominant-negative mutant form of cullin 5 in HeLa cells before infection with wild-type Ad5 or the E1B-55K null mutant dl1520. The dominant-negative cullin 5 protein stabilized p53 and the MRN complex, indicating that it inhibited the viral ubiquitin-protein ligase but had no effect on viral early mRNA synthesis, early protein synthesis, or viral DNA replication. However, expression of the dominant-negative cullin 5 protein caused a decrease in viral late protein synthesis and viral nuclear mRNA export similar to the phenotype produced by mutations in E1B-55K. We conclude that the stimulation of adenovirus late mRNA nuclear export by E1B-55K and E4orf6 results from the ubiquitin-protein ligase activity of the adenovirus ubiquitin-protein ligase complex.

Mapping of cellular protein-binding sites on the products of early-region 1A of human adenovirus type 5

1988 ◽  
Vol 8 (9) ◽  
pp. 3955-3959 ◽  
Author(s):  
C Egan ◽  
T N Jelsma ◽  
J A Howe ◽  
S T Bayley ◽  
B Ferguson ◽  
...  
Keyword(s):  
Biological Activity ◽  
Binding Sites ◽  
Human Adenovirus ◽  
Adenovirus Type ◽  
Cellular Protein ◽  
Cellular Proteins ◽  
Deletion Mutants ◽  
Protein Binding Sites ◽  
Amino Terminal ◽  
Adenovirus Type 5

The binding sites for the 300-, 107-, and 105-kilodalton cellular proteins which associate with human adenovirus type 5 E1A products were studied with E1A deletion mutants. All appeared to bind to the amino-terminal half of E1A products in regions necessary for oncogenic transformation. These results suggest that these cellular species may be important for the biological activity of E1A products.

scholarly journals Proteomic Analysis of Ubiquitin-Like Posttranslational Modifications Induced by the Adenovirus E4-ORF3 Protein

2014 ◽  
Vol 89 (3) ◽  
pp. 1744-1755 ◽  
Author(s):  
Sook-Young Sohn ◽  
Rebecca G. Bridges ◽  
Patrick Hearing
Keyword(s):  
Structural Changes ◽  
Human Adenovirus ◽  
Cellular Protein ◽  
Interferon Response ◽  
Global Pattern ◽  
Diverse Range ◽  
Orf3 Protein ◽  
Antiviral Responses ◽  
Early Protein ◽  
Infected Cells

ABSTRACTViruses interact with and regulate many host metabolic pathways in order to advance the viral life cycle and counteract intrinsic and extrinsic antiviral responses. The human adenovirus (Ad) early protein E4-ORF3 forms a unique scaffold throughout the nuclei of infected cells and inhibits multiple antiviral defenses, including a DNA damage response (DDR) and an interferon response. We previously reported that the Ad5 E4-ORF3 protein induces sumoylation of Mre11 and Nbs1, which are essential for the DDR, and their relocalization into E4-ORF3-induced nuclear inclusions is required for this modification to occur. In this study, we sought to analyze a global change in ubiquitin-like (Ubl) modifications, with particular focus on SUMO3, by the Ad5 E4-ORF3 protein and to identify new substrates with these modifications. By a comparative proteome-wide approach utilizing immunoprecipitation/mass spectrometry, we found that Ubl modifications of 166 statistically significant lysine sites in 51 proteins are affected by E4-ORF3, and the proteome of modifications spans a diverse range of cellular functions. Ubl modifications of 92% of these identified sites were increased by E4-ORF3. We further analyzed SUMO3 conjugation of several identified proteins. Our findings demonstrated a role for the Ad5 E4-ORF3 protein as a regulator of Ubl modifications and revealed new SUMO3 substrates induced by E4-ORF3.IMPORTANCEThe adenovirus E4-ORF3 protein induces dynamic structural changes in the nuclei of infected cells and counteracts host antiviral responses. One of the mechanisms that accounts for this process is the relocalization and sequestration of cellular proteins into an E4-ORF3 nuclear scaffold, but little is known about how this small viral protein affects diverse cellular responses. In this study, we analyzed for the first time the global pattern of ubiquitin-like (Ubl) modifications, with particular focus on SUMO3, altered by E4-ORF3 expression. The results suggest a role for the Ad5 E4-ORF3 protein as a regulator of Ubl modifications and reveal new SUMO3 substrates targeted by E4-ORF3. Our findings propose Ubl modifications as a new mechanism by which E4-ORF3 may modulate cellular protein functions in addition to subnuclear relocalization.

scholarly journals Distinct Requirements of Adenovirus E1b55K Protein for Degradation of Cellular Substrates

2008 ◽  
Vol 82 (18) ◽  
pp. 9043-9055 ◽  
Author(s):  
Rachel A. Schwartz ◽  
Seema S. Lakdawala ◽  
Heather D. Eshleman ◽  
Matthew R. Russell ◽  
Christian T. Carson ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Adenovirus Type ◽  
Cellular Proteins ◽  
Mutant Proteins ◽  
Ubiquitin Ligase Activity ◽  
Late Protein ◽  
Ligase Iv ◽  
Cullin 5 ◽  
Cellular Dna ◽  
Mutant Forms

ABSTRACT The E1b55K and E4orf6 proteins of adenovirus type 5 (Ad5) assemble into a complex together with cellular proteins including cullin 5, elongins B and C, and Rbx1. This complex possesses E3 ubiquitin ligase activity and targets cellular proteins for proteasome-mediated degradation. The ligase activity has been suggested to be responsible for all functions of E1b55K/E4orf6, including promoting efficient viral DNA replication, preventing a cellular DNA damage response, and stimulating late viral mRNA nuclear export and late protein synthesis. The known cellular substrates for degradation by E1b55K/E4orf6 are the Mre11/Rad50/Nbs1 DNA repair complex, the tumor suppressor p53, and DNA ligase IV. Here we show that the degradation of individual targets can occur independently of other substrates. Furthermore, we identify separation-of-function mutant forms of E1b55K that can distinguish substrates for binding and degradation. Our results identify distinct regions of E1b55K that are involved in substrate recognition but also imply that there are additional requirements beyond protein association. These mutant proteins will facilitate the determination of the relevance of specific substrates to the functions of E1b55K in promoting infection and inactivating host defenses.

Effects of adenovirus infection on rRNA synthesis and maturation in HeLa cells

1983 ◽  
Vol 3 (4) ◽  
pp. 662-671
Author(s):  
C L Castiglia ◽  
S J Flint
Keyword(s):  
Hela Cells ◽  
Ribosomal Proteins ◽  
18S Rrna ◽  
Adenovirus Type ◽  
Cellular Protein ◽  
Rrna Synthesis ◽  
28S Rrna ◽  
Adenovirus Infection ◽  
Infected Cells ◽  
Infectious Cycle

The production of cytoplasmic and nucleolar rRNA species was examined in HeLa cells infected with high multiplicities of adenovirus type 5. Both 28S and 18S rRNA newly synthesized in infected cells ceased to enter the cytoplasm as reported previously (N. Ledinko, Virology 49: 79-89, 1972; H. J. Raskas, D. C. Thomas, and M. Green, Virology 40: 893-902, 1970). However, the effects on 28S cytoplasmic rRNA were observed considerably earlier in the infectious cycle than those on 18S rRNA. The inhibition of cellular protein synthesis and of the appearance in the cytoplasm of labeled cellular mRNA sequences (G. A. Beltz and S. J. Flint, J. Mol. Biol. 131: 353-373, 1979) were also monitored in infected cultures. During the later periods of an infectious cycle, from 18 h after infection, nucleolar rRNA synthesis and processing and exit of 18S rRNA from the nucleus were inhibited, probably reflecting the failure of infected cells to synthesize normal quantities of ribosomal proteins. The earliest responses of cellular RNA metabolism to adenovirus infection were, however, the rapid and apparently coordinate reductions in the levels of newly synthesized 28S rRNA and cellular mRNA sequences entering the cytoplasm.

scholarly journals Effects of adenovirus infection on rRNA synthesis and maturation in HeLa cells.

1983 ◽  
Vol 3 (4) ◽  
pp. 662-671 ◽  
Author(s):  
C L Castiglia ◽  
S J Flint
Keyword(s):  
Hela Cells ◽  
Ribosomal Proteins ◽  
18S Rrna ◽  
Adenovirus Type ◽  
Cellular Protein ◽  
Rrna Synthesis ◽  
28S Rrna ◽  
Adenovirus Infection ◽  
Infected Cells ◽  
Infectious Cycle

The production of cytoplasmic and nucleolar rRNA species was examined in HeLa cells infected with high multiplicities of adenovirus type 5. Both 28S and 18S rRNA newly synthesized in infected cells ceased to enter the cytoplasm as reported previously (N. Ledinko, Virology 49: 79-89, 1972; H. J. Raskas, D. C. Thomas, and M. Green, Virology 40: 893-902, 1970). However, the effects on 28S cytoplasmic rRNA were observed considerably earlier in the infectious cycle than those on 18S rRNA. The inhibition of cellular protein synthesis and of the appearance in the cytoplasm of labeled cellular mRNA sequences (G. A. Beltz and S. J. Flint, J. Mol. Biol. 131: 353-373, 1979) were also monitored in infected cultures. During the later periods of an infectious cycle, from 18 h after infection, nucleolar rRNA synthesis and processing and exit of 18S rRNA from the nucleus were inhibited, probably reflecting the failure of infected cells to synthesize normal quantities of ribosomal proteins. The earliest responses of cellular RNA metabolism to adenovirus infection were, however, the rapid and apparently coordinate reductions in the levels of newly synthesized 28S rRNA and cellular mRNA sequences entering the cytoplasm.

scholarly journals The Adenovirus E4-ORF3 Protein Stimulates SUMOylation of General Transcription Factor TFII-I to Direct Proteasomal Degradation

mBio ◽  
2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Rebecca G. Bridges ◽  
Sook-Young Sohn ◽  
Jordan Wright ◽  
Keith N. Leppard ◽  
Patrick Hearing
Keyword(s):  
Transcription Factor ◽  
Viral Protein ◽  
Proteasomal Degradation ◽  
Cellular Proteins ◽  
Viral Promoter ◽  
Orf3 Protein ◽  
Antiviral Responses ◽  
General Transcription Factor ◽  
Infected Cells ◽  
Insight Into

ABSTRACT Modulation of host cell transcription, translation, and posttranslational modification processes is critical for the ability of many viruses to replicate efficiently within host cells. The human adenovirus (Ad) early region 4 open reading frame 3 (E4-ORF3) protein forms unique inclusions throughout the nuclei of infected cells and inhibits the antiviral Mre11-Rad50-Nbs1 DNA repair complex through relocalization. E4-ORF3 also induces SUMOylation of Mre11 and Nbs1. We recently identified additional cellular targets of E4-ORF3 and found that E4-ORF3 stimulates ubiquitin-like modification of 41 cellular proteins involved in a wide variety of processes. Among the proteins most abundantly modified in an E4-ORF3-dependent manner was the general transcription factor II–I (TFII-I). Analysis of Ad-infected cells revealed that E4-ORF3 induces TFII-I relocalization and SUMOylation early during infection. In the present study, we explored the relationship between E4-ORF3 and TFII-I. We found that Ad infection or ectopic E4-ORF3 expression leads to SUMOylation of TFII-I that precedes a rapid decline in TFII-I protein levels. We also show that E4-ORF3 is required for ubiquitination of TFII-I and subsequent proteasomal degradation. This is the first evidence that E4-ORF3 regulates ubiquitination. Interestingly, we found that E4-ORF3 modulation of TFII-I occurs in diverse cell types but only E4-ORF3 of Ad species C regulates TFII-I, providing critical insight into the mechanism by which E4-ORF3 targets TFII-I. Finally, we show that E4-ORF3 stimulates the activity of a TFII-I-repressed viral promoter during infection. Our results characterize a novel mechanism of TFII-I regulation by Ad and highlight how a viral protein can modulate a critical cellular transcription factor during infection. IMPORTANCE Adenovirus has evolved a number of mechanisms to target host signaling pathways in order to optimize the cellular environment during infection. E4-ORF3 is a small viral protein made early during infection, and it is critical for inactivating host antiviral responses. In addition to its ability to capture and reorganize cellular proteins, E4-ORF3 also regulates posttranslational modifications of target proteins, but little is known about the functional consequences of these modifications. We recently identified TFII-I as a novel target of E4-ORF3 that is relocalized into dynamic E4-ORF3 nuclear structures and subjected to E4-ORF3-mediated SUMO modification. Here, we show that TFII-I is targeted by E4-ORF3 for ubiquitination and proteasomal degradation and that E4-ORF3 stimulates gene expression from a TFII-I-repressed viral promoter. Our findings suggest that the specific targeting of TFII-I by E4-ORF3 is a mechanism to inactivate its antiviral properties. These studies provide further insight into how E4-ORF3 functions to counteract host antiviral responses.

scholarly journals Mapping of cellular protein-binding sites on the products of early-region 1A of human adenovirus type 5.

1988 ◽  
Vol 8 (9) ◽  
pp. 3955-3959 ◽  
Author(s):  
C Egan ◽  
T N Jelsma ◽  
J A Howe ◽  
S T Bayley ◽  
B Ferguson ◽  
...  
Keyword(s):  
Biological Activity ◽  
Binding Sites ◽  
Human Adenovirus ◽  
Adenovirus Type ◽  
Cellular Protein ◽  
Cellular Proteins ◽  
Deletion Mutants ◽  
Protein Binding Sites ◽  
Amino Terminal ◽  
Adenovirus Type 5

The binding sites for the 300-, 107-, and 105-kilodalton cellular proteins which associate with human adenovirus type 5 E1A products were studied with E1A deletion mutants. All appeared to bind to the amino-terminal half of E1A products in regions necessary for oncogenic transformation. These results suggest that these cellular species may be important for the biological activity of E1A products.

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