scholarly journals Characterization of human herpesvirus 6 variant B immediate-early 1 protein modifications by small ubiquitin-related modifiers

2004 ◽  
Vol 85 (5) ◽  
pp. 1319-1328 ◽  
Author(s):  
Annie Gravel ◽  
Valérie Dion ◽  
Nathalie Cloutier ◽  
Jean Gosselin ◽  
Louis Flamand
Keyword(s):  
Biochemical Characterization ◽  
Human Herpesvirus ◽  
Immediate Early ◽  
Human Herpesvirus 6 ◽  
Post Translational Modifications ◽  
Sumo Conjugation ◽  
Complex Interactions ◽  
Herpesvirus 6

The human herpesvirus 6 (HHV-6) immediate-early (IE) 1 protein undergoes SUMOylation events during the infectious process. In the present work, we report that Lys-802 (K-802) of IE1 from HHV-6 variant B is the only target residue capable of conjugation to SUMO-1/SMT3C/Sentrin-1, SUMO-2/SMT3A/Sentrin-3 or SUMO-3/SMT3B/Sentrin-2 as determined by transfection and in vitro SUMOylation experiments. PolySUMOylated forms of IE1 were also observed, suggesting that SUMO branching occurs at the K-802 residue. Overexpression of SUMO-1, -2 and -3 led to an overall increase in IE1 levels, irrespective of K-802. The SUMO residues could be efficiently removed by incubating SUMOylated IE1 with SENP1, a recently identified SUMO peptidase. SUMOylation-deficient mutants of IE1 co-localized with nuclear promyelocytic leukaemia protein (PML) oncogenic domains (PODs) as efficiently as WT IE1, indicating that POD targeting is independent of IE1 SUMOylation status. However, in contrast to infection, PODs did not aggregate in IE1B-transfected cells, suggesting that other viral proteins are involved in the process. Transactivation studies indicated that IE1, in combination with IE2, could efficiently transactivate diverse promoters, independent of its SUMOylation status. Overall, the results presented provide a detailed biochemical characterization of post-translational modifications of the HHV-6 IE1 protein by SUMO peptides, contributing to our understanding of the complex interactions between herpesviruses and the SUMO-conjugation pathway.

scholarly journals Functional Interaction between Human Herpesvirus 6 Immediate-Early 2 Protein and Ubiquitin-Conjugating Enzyme 9 in the Absence of Sumoylation

2006 ◽  
Vol 80 (20) ◽  
pp. 10218-10228 ◽  
Author(s):  
Andru Tomoiu ◽  
Annie Gravel ◽  
Robert M. Tanguay ◽  
Louis Flamand
Keyword(s):  
Human Herpesvirus ◽  
Immediate Early ◽  
Human Herpesvirus 6 ◽  
Interacting Protein ◽  
Ubiquitin Conjugating Enzyme ◽  
Herpesvirus 6 ◽  
Transcriptional Complex ◽  
Conjugating Enzyme

ABSTRACT The immediate-early 2 (IE2) protein of human herpesvirus 6 is a potent transactivator of cellular and viral promoters. To better understand the biology of IE2, we generated a LexA-IE2 fusion protein and screened, using the yeast two-hybrid system, a Jurkat T-cell cDNA library for proteins that could interact with IE2. The most frequently isolated IE2-interacting protein was the human ubiquitin-conjugating enzyme 9 (Ubc9), a protein involved in the small ubiquitin-like modifier (SUMO) conjugation pathway. Using deletion mutants of IE2, we mapped the IE2-Ubc9-interacting region to residues 989 to 1037 of IE2. The interaction was found to be of functional significance to IE2, as Ubc9 overexpression significantly repressed promoter activation by IE2. The C93S Ubc9 mutant exhibited a similar effect on IE2, indicating that the E2 SUMO-conjugating function of Ubc9 is not required for its repressive action on IE2. No consensus sumoylation sites or evidence of IE2 conjugation to SUMO could be demonstrated under in vivo or in vitro conditions. Moreover, expression levels and nuclear localization of IE2 were not altered by Ubc9 overexpression, suggesting that Ubc9's repressive function likely occurs at the transcriptional complex level. Overall, our results indicate that Ubc9 influences IE2's function and provide new information on the complex interactions that occur between herpesviruses and the sumoylation pathway.

scholarly journals Recognition of a Novel Stage of Betaherpesvirus Latency in Human Herpesvirus 6

2003 ◽  
Vol 77 (3) ◽  
pp. 2258-2264 ◽  
Author(s):  
Kazuhiro Kondo ◽  
Junji Sashihara ◽  
Kazuya Shimada ◽  
Masaya Takemoto ◽  
Kiyoko Amo ◽  
...  
Keyword(s):  
Human Herpesvirus ◽  
Intermediate Stage ◽  
Viral Reactivation ◽  
Immediate Early ◽  
Human Herpesvirus 6 ◽  
Early Protein ◽  
Stable Intermediate ◽  
Herpesvirus 6

ABSTRACT Latency-associated transcripts of human herpesvirus 6 (H6LTs) (K. Kondo et al. J. Virol. 76:4145-4151, 2002) were maximally expressed at a fairly stable intermediate stage between latency and reactivation both in vivo and in vitro. H6LTs functioned as sources of immediate-early protein 1 at this stage, which up-regulated the viral reactivation.

scholarly journals Characterization of the immediate-early 2 protein of human herpesvirus 6, a promiscuous transcriptional activator

Virology ◽  
2003 ◽  
Vol 308 (2) ◽  
pp. 340-353 ◽  
Author(s):  
Annie Gravel ◽  
Andru Tomoiu ◽  
Nathalie Cloutier ◽  
Jean Gosselin ◽  
Louis Flamand
Keyword(s):  
Human Herpesvirus ◽  
Transcriptional Activator ◽  
Immediate Early ◽  
Human Herpesvirus 6 ◽  
Herpesvirus 6

61: In vitro selection and characterization of human herpesvirus 6 strains resistant to foscarnet or cidofovir

2006 ◽  
Vol 37 ◽  
pp. S113-S114
Author(s):  
P. Bonnafous ◽  
L. Naesens ◽  
A. Gautheret-Dejean ◽  
D. Boutolleau ◽  
E. De Clercq ◽  
...  
Keyword(s):  
In Vitro Selection ◽  
Human Herpesvirus ◽  
Human Herpesvirus 6 ◽  
Herpesvirus 6

scholarly journals In vitro cellular tropism of human B-lymphotropic virus (human herpesvirus-6).

1988 ◽  
Vol 167 (5) ◽  
pp. 1659-1670 ◽  
Author(s):  
P Lusso ◽  
P D Markham ◽  
E Tschachler ◽  
F di Marzo Veronese ◽  
S Z Salahuddin ◽  
...  
Keyword(s):  
T Cell ◽  
T Lymphocytes ◽  
Cell Population ◽  
Mononuclear Cells ◽  
Human Herpesvirus ◽  
Human Herpesvirus 6 ◽  
Infected Cells ◽  
Cellular Tropism ◽  
Herpesvirus 6

We investigated the cellular tropism of human B-lymphotropic virus (HBLV) (also designated Human Herpesvirus-6) in vitro by infecting fresh MN cells from normal human adult peripheral blood, umbilical cord blood, bone marrow, tonsil, and thymus. Cultures from all the sources examined contained infectable cells, as shown by the appearance of characteristic enlarged, round-shaped, short-lived cells expressing HBLV-specific markers. Detailed immunological analysis demonstrated that the vast majority of these cells expressed T cell-associated antigens (i.e., CD7, CD5, CD2, CD4, and to a lesser extent, CD8). The CD3 antigen and the TCR-alpha/beta heterodimer were not detectable on the surface membrane, but were identified within the cytoplasm of HBLV-infected cells, by both immunofluorescence and radioimmunoprecipitation assay. A proportion of the HBLV-infected cell population also expressed the CD15 and class II MHC DR antigens. By means of immunoselection procedures it was possible to show that a consistent proportion of HBLV-infectable cells were contained within the CD3-depleted immature T cell population, while the depletion of CD2+ cells completely abrogated the infectability of the cultures. Northern blot analysis confirmed the T cell origin of HBLV-infected cells, demonstrating the expression of full size TCR-alpha and -beta chain mRNA. In addition to fresh T cells, HBLV was able to infect normal T lymphocytes expanded in vitro with IL-2 for greater than 30 d. These results indicate that HBLV is selectively T cell tropic in the course of the in vitro infection of normal mononuclear cells and may therefore be directly involved in the pathogenesis of T cell related hematological disorders. In particular, in light of the cytopathic effect exerted in vitro on CD4+ T lymphocytes, a possible role of HBLV in immune deficiency conditions should be considered.

In vitro sensitivity of human herpesvirus-6 to antiviral drugs

1989 ◽  
Vol 140 ◽  
pp. 219-228 ◽  
Author(s):  
H. Agut ◽  
H. Collandre ◽  
J.-T. Aubin ◽  
D. Guétard ◽  
V. Favier ◽  
...  
Keyword(s):  
Human Herpesvirus ◽  
Antiviral Drugs ◽  
Human Herpesvirus 6 ◽  
In Vitro Sensitivity ◽  
Herpesvirus 6
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