Herpes simplex virus type 2 tegument protein UL56 relocalizes ubiquitin ligase Nedd4 and has a role in transport and/or release of virions

<p>Abstract</p> <p>Background</p> <p>The ubiquitin system functions in a variety of cellular processes including protein turnover, protein sorting and trafficking. Many viruses exploit the cellular ubiquitin system to facilitate viral replication. In fact, herpes simplex virus (HSV) encodes a ubiquitin ligase (E3) and a de-ubiquitinating enzyme to modify the host's ubiquitin system. We have previously reported HSV type 2 (HSV-2) tegument protein UL56 as a putative adaptor protein of neuronal precursor cell-expressed developmentally down-regulated 4 (Nedd4) E3 ligase, which has been shown to be involved in protein sorting and trafficking.</p> <p>Results</p> <p>In this study, we visualized and characterized the dynamic intracellular localization of UL56 and Nedd4 using live-cell imaging and immunofluorescence analysis. UL56 was distributed to cytoplasmic vesicles, primarily to the trans-Golgi network (TGN), and trafficked actively throughout the cytoplasm. Moreover, UL56 relocalized Nedd4 to the vesicles in cells transiently expressing UL56 and in cells infected with HSV-2. We also investigated whether UL56 influenced the efficiency of viral replication, and found that extracellular infectious viruses were reduced in the absence of UL56.</p> <p>Conclusion</p> <p>These data suggest that UL56 regulates Nedd4 and functions to facilitate the cytoplasmic transport of virions from TGN to the plasma membrane and/or release of virions from the cell surface.</p

Herpes simplex virus induces the marked up-regulation of the zinc finger transcriptional factor INSM1, which modulates the expression and localization of the immediate early protein ICP0

<p>Abstract</p> <p>Background</p> <p>Herpes simplex viruses (HSVs) rapidly shut off macromolecular synthesis in host cells. In contrast, global microarray analyses have shown that HSV infection markedly up-regulates a number of host cell genes that may play important roles in HSV-host cell interactions. To understand the regulatory mechanisms involved, we initiated studies focusing on the zinc finger transcription factor insulinoma-associated 1 (INSM1), a host cell protein markedly up-regulated by HSV infection.</p> <p>Results</p> <p>INSM1 gene expression in HSV-1-infected normal human epidermal keratinocytes increased at least 400-fold 9 h after infection; INSM1 promoter activity was also markedly stimulated. Expression and subcellular localization of the immediate early HSV protein ICP0 was affected by INSM1 expression, and chromatin immunoprecipitation (ChIP) assays revealed binding of INSM1 to the ICP0 promoter. Moreover, the role of INSM1 in HSV-1 infection was further clarified by inhibition of HSV-1 replication by INSM1-specific siRNA.</p> <p>Conclusions</p> <p>The results suggest that INSM1 up-regulation plays a positive role in HSV-1 replication, probably by binding to the ICP0 promoter.</p

Herpes simplex virus type 1 UL14 tegument protein regulates intracellular compartmentalization of major tegument protein VP16

<p>Abstract</p> <p>Background</p> <p>Herpes simplex virus type 1 (HSV-1) has a complicated life-cycle, and its genome encodes many components that can modify the cellular environment to facilitate efficient viral replication. The protein UL14 is likely involved in viral maturation and egress (Cunningham C. et al), and it facilitates the nuclear translocation of viral capsids and the tegument protein VP16 during the immediate-early phase of infection (Yamauchi Y. et al, 2008). UL14 of herpes simplex virus type 2 exhibits multiple functions (Yamauchi Y. et al, 2001, 2002, 2003).</p> <p>Methods</p> <p>To better understand the function(s) of UL14, we generated VP16-GFP-incorporated UL14-mutant viruses with either single (K51M) or triple (R60A, R64A, E68D) amino acid substitutions in the heat shock protein (HSP)-like sequence of UL14. We observed the morphology of cells infected with UL14-null virus and amino acid-substituted UL14-mutant viruses at different time points after infection.</p> <p>Results</p> <p>UL14(3P)-VP16GFP and UL14D-VP16GFP (UL14-null) viruses caused similar defects with respect to growth kinetics, compartmentalization of tegument proteins, and cellular morphology in the late phase. Both the UL14D-VP16GFP and UL14(3P)-VP16GFP viruses led to the formation of an aggresome that incorporated some tegument proteins but did not include nuclear-egressed viral capsids.</p> <p>Conclusions</p> <p>Our findings suggest that a cluster of charged residues within the HSP-like sequence of UL14 is important for the molecular chaperone-like functions of UL14, and this activity is required for the acquisition of functionality of VP16 and UL46. In addition, UL14 likely contributes to maintaining cellular homeostasis following infection, including cytoskeletal organization. However, direct interactions between UL14 and VP16, UL46, or other cellular or viral proteins remain unclear.</p

Kraus representation in the presence of initial correlations

We examine the validity of the Kraus representation in the presence of initial correlations and show that it is assured only when a joint dynamics is locally unitary.Comment: REVTeX4, 12 page

Herpes simplex virus UL56 interacts with and regulates the Nedd4-family ubiquitin ligase Itch

<p>Abstract</p> <p>Background</p> <p>Herpes simplex virus type 2 (HSV-2) is one of many viruses that exploits and modifies the cellular ubiquitin system. HSV-2 expresses the tegument protein UL56 that has been implicated in cytoplasmic transport and/or release of virions, and is a putative regulatory protein of Nedd4 ubiquitin ligase. In order to elucidate the biological function of UL56, this study examined the interaction of UL56 with the Nedd4-family ubiquitin ligase Itch and its role in the regulation of Itch. Additionally, we assessed the similarity between UL56 and regulatory proteins of Itch and Nedd4, Nedd4-family-interactins proteins (Ndfip).</p> <p>Results</p> <p>UL56 interacted with Itch, independent of additional viral proteins, and mediated more striking degradation of Itch, compared to Nedd4. Moreover, it was suggested that the lysosome pathway as well as the proteasome pathway was involved in the degradation of Itch. Other HSV-2 proteins with PY motifs, such as VP5 and VP16, did not mediate the degradation of endogenous Itch. Ndfip1 and Ndfip2 were similar in subcellular distribution patterns to UL56 and colocalized with UL56 in co-transfected cells.</p> <p>Conclusions</p> <p>We believe that this is the first report demonstrating the interaction of a HSV-specific protein and Itch. Thus, UL56 could function as a regulatory protein of Itch. The mechanism, function and significance of regulating Itch in HSV-2 infection remain unclear and warrant further investigation.</p

Immunization with a highly attenuated replication-competent herpes simplex virus type 1 mutant, HF10, protects mice from genital disease caused by herpes simplex virus type 2

Genital herpes is an intractable disease caused mainly by herpes simplex virus (HSV) type 2 (HSV-2), and is a major concern in public health. A previous infection with HSV type 1 (HSV-1) enhances protection against primary HSV-2 infection to some extent. In this study, we evaluated the ability of HF10, a naturally occurring replication-competent HSV-1 mutant, to protect against genital infection in mice caused by HSV-2. Subcutaneous inoculation of HF10-immunized mice against lethal infection by HSV-2, and attenuated the development of genital ulcer diseases. Immunization with HF10 inhibited HSV-2 replication in the mouse vagina, reduced local inflammation, controlled emergence of neurological dysfunctions of HSV-2 infection, and increased survival. In HF10-immunized mice, we observed rapid and increased production of interferon-γ in the vagina in response to HSV-2 infection, and numerous CD4+ and a few CD8+ T cells localized to the infective focus. CD4+ T cells invaded the mucosal subepithelial lamina propria. Thus, the protective effect of HF10 was related to induction of cellular immunity, mediated primarily by Th1 CD4+ cells. These data indicate that the live attenuated HSV-1 mutant strain HF10 is a promising candidate antigen for a vaccine against genital herpes caused by HSV-2

Metal cations modulate the bacteriochlorophyll–protein interaction in the light-harvesting 1 core complex from Thermochromatium tepidum

AbstractThe light-harvesting 1 reaction center (LH1-RC) complex from Thermochromatium (Tch.) tepidum exhibits unusual Qy absorption by LH1 bacteriochlorophyll-a (BChl-a) molecules at 915nm, and the transition energy is finely modulated by the binding of metal cations to the LH1 polypeptides. Here, we demonstrate the metal-dependent interactions between BChl-a and the polypeptides within the intact LH1-RC complexes by near-infrared Raman spectroscopy. The wild-type LH1-RC (B915) exhibited Raman bands for the C3-acetyl and C13-keto CO stretching modes at 1637 and 1675cm−1, respectively. The corresponding bands appeared at 1643 and 1673cm−1 when Ca2+ was biosynthetically replaced with Sr2+ (B888) or at 1647 and 1669cm−1 in the mesophilic counterpart, Allochromatium vinosum. These results indicate the significant difference in the BChl–polypeptide interactions between B915 and B888 and between B915 and the mesophilic counterpart. The removal of the original metal cations from B915 and B888 resulted in marked band shifts of the C3-acetyl/C13-carbonyl νCO modes to ~1645/~1670cm−1, supporting a model in which the metal cations are involved in the fine-tuning of the hydrogen bonding between the BChl-a and LH1-polypeptides. Interestingly, the interaction modes were almost identical between the Ca2+-depleted B915 and Sr2+-depleted B888 and between B915 and Ca2+-substituted B888, despite the significant differences in their LH1 Qy peak positions and the denaturing temperatures, as revealed by differential scanning calorimetry. These results suggest that not only the BChl–polypeptide interactions but some structural origin may be involved in the unusual Qy red-shift and the enhanced thermal stability of the LH1-RC complexes from Tch. tepidum