scholarly journals The HSV-1 immediate early protein ICP22 is a J-like protein required for Hsc70 reorganization during lytic infection

2019 ◽  
Author(s):  
Mitali Adlakha ◽  
Christine M. Livingston ◽  
Irina Bezsonova ◽  
Sandra K. Weller
Keyword(s):  
Gene Expression ◽  
Lytic Infection ◽  
Immediate Early ◽  
Misfolded Proteins ◽  
Native Proteins ◽  
Early Protein ◽  
J Proteins ◽  
J Domain ◽  
Nuclear Domains ◽  
J Protein

ABSTRACTMolecular chaperones and co-chaperones are the most abundant cellular effectors of protein homeostasis, assisting protein folding and preventing aggregation of misfolded proteins. We have previously shown that HSV-1 infection results in the drastic spatial reorganization of the cellular chaperone Hsc70 into nuclear domains called VICE (VirusInducedChaperoneEnriched) domains and that this recruitment is dependent on the viral immediate early protein ICP22. In this paper, we present several lines of evidence supporting the notion that ICP22 functions as a virally encoded co-chaperone (J-protein/Hsp40) functioning together with its Hsc70 partner to recognize and manage aggregated and misfolded proteins. We show that ICP22 results in (i) nuclear sequestration of non-native proteins, (ii) reduction of cytoplasmic aggresomes in cells expressing aggregation-prone proteins and (iii) thermoprotection against heat-inactivation of firefly luciferase. (iv) Sequence homology analysis indicated that ICP22 contains an N-terminal J-domain and a C-terminal substrate binding domain, similar to type II cellular J-proteins. ICP22 may, thus, be functionally similar to J-protein/Hsp40 co-chaperones that function together with their HSP70 partners to prevent aggregation of non-native proteins. This is not the first example of a virus hijacking a function of a cellular chaperone, as SV40 T Antigen was previously shown to contain a J-domain; however, this the first known example of the acquisition of a complete J-like protein by a virus and suggests that HSV has taken advantage of the adaptable nature of J-proteins to evolve a multi-functional co-chaperone that functions with Hsc70 to promote lytic infection.IMPORTANCEViruses have evolved a variety of strategies to succeed in a hostile environment. The HSV immediate early protein ICP22 plays several roles in the virus life cycle including down-regulation of cellular gene expression, up-regulation of late viral gene expression, inhibition of apoptosis, prevention of aggregation of non-native proteins and the recruitment of a cellular heat shock protein, Hsc70, to nuclear domains. We present evidence that ICP22 resembles a cellular J-protein/HSP40 family co-chaperone, interacting specifically with Hsc70. This is the first known example of the acquisition of a complete J-like protein by a virus and suggests that HSV has evolved to manipulate the host proteostatic machinery during the establishment of lytic infection.

scholarly journals The Herpes Simplex Virus 1 Immediate Early Protein ICP22 Is a Functional Mimic of a Cellular J Protein

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Mitali Adlakha ◽  
Christine M. Livingston ◽  
Irina Bezsonova ◽  
Sandra K. Weller
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Immediate Early ◽  
Herpes Simplex Virus 1 ◽  
Early Protein ◽  
J Proteins ◽  
J Domain ◽  
Nuclear Domains ◽  
Simplex Virus ◽  
J Protein

ABSTRACT Molecular chaperones and cochaperones are the most abundant cellular effectors of protein homeostasis, assisting protein folding and preventing aggregation of misfolded proteins. We have previously shown that herpes simplex virus 1 (HSV-1) infection results in the drastic spatial reorganization of the cellular chaperone Hsc70 into nuclear domains called VICE (Virus Induced Chaperone Enriched) domains and that this recruitment is dependent on the viral immediate early protein ICP22. Here, we present several lines of evidence supporting the notion that ICP22 functions as a virally encoded cochaperone (J-protein/Hsp40) functioning together with its Hsc70 partner to recognize and manage aggregated and misfolded proteins. We show that ICP22 results in (i) nuclear sequestration of nonnative proteins, (ii) reduction of cytoplasmic aggresomes in cells expressing aggregation-prone proteins, and (iii) thermoprotection against heat inactivation of firefly luciferase, and (iv) sequence homology analysis indicated that ICP22 contains an N-terminal J domain and a C-terminal substrate binding domain, similar to type II cellular J proteins. ICP22 may thus be functionally similar to J-protein/Hsp40 cochaperones that function together with their HSP70 partners to prevent aggregation of nonnative proteins. This is not the first example of a virus hijacking a function of a cellular chaperone, since simian immunodeficiency virus T antigen was previously shown to contain a J domain; however, this the first known example of the acquisition of a functional J-like protein by a virus and suggests that HSV has taken advantage of the adaptable nature of J proteins to evolve a multifunctional cochaperone that functions with Hsc70 to promote lytic infection. IMPORTANCE Viruses have evolved a variety of strategies to succeed in a hostile environment. The herpes simplex virus 1 (HSV-1) immediate early protein ICP22 plays several roles in the virus life cycle, including downregulation of cellular gene expression, upregulation of late viral gene expression, inhibition of apoptosis, prevention of aggregation of nonnative proteins, and the recruitment of a cellular heat shock protein, Hsc70, to nuclear domains. We present evidence that ICP22 functionally resembles a cellular J-protein/HSP40 family cochaperone, interacting specifically with Hsc70. We suggest that HSV has taken advantage of the adaptable nature of J proteins to evolve a multifunctional cochaperone that functions with Hsc70 to promote lytic infection.

scholarly journals The Cellular Coactivator HCF-1 Is Required for Glucocorticoid Receptor-Mediated Transcription of Bovine Herpesvirus 1 Immediate Early Genes

2018 ◽  
Vol 92 (17) ◽  
Author(s):  
Laximan Sawant ◽  
Insun Kook ◽  
Jodi L. Vogel ◽  
Thomas M. Kristie ◽  
Clinton Jones
Keyword(s):  
Gene Expression ◽  
Glucocorticoid Receptor ◽  
Bovine Herpesvirus ◽  
Transcription Unit ◽  
Lytic Infection ◽  
Immediate Early ◽  
Productive Infection ◽  
Core Element ◽  
Bovine Herpesvirus 1 ◽  
Herpesvirus 1

ABSTRACTFollowing productive infection, bovine herpesvirus 1 (BoHV-1) establishes latency in sensory neurons. As in other alphaherpesviruses, expression of BoHV-1 immediate early (IE) genes is regulated by an enhancer complex containing the viral IE activator VP16, the cellular transcription factor Oct-1, and transcriptional coactivator HCF-1, which is assembled on an IE enhancer core element (TAATGARAT). Expression of the IE transcription unit that encodes the viral IE activators bICP0 and bICP4 may also be induced by the activated glucocorticoid receptor (GR) via two glucocorticoid response elements (GREs) located upstream of the enhancer core. Strikingly, lytic infection and reactivation from latency are consistently enhanced by glucocorticoid treatmentin vivo. As the coactivator HCF-1 is essential for IE gene expression of alphaherpesviruses and recruited by multiple transcription factors, we tested whether HCF-1 is required for glucocorticoid-induced IE gene expression. Depletion of HCF-1 reduced GR-mediated activation of the IE promoter in mouse neuroblastoma cells (Neuro-2A). More importantly, HCF-1-mediated GR activation of the promoter was dependent on the presence of GRE sites but independent of the TAATGARAT enhancer core element. HCF-1 was also recruited to the GRE region of a promoter lacking the enhancer core, consistent with a direct role of the coactivator in mediating GR-induced transcription. Similarly, during productive lytic infection, HCF-1 and GR occupied the IE region containing the GREs. These studies indicate HCF-1 is critical for GR activation of the viral IE genes and suggests that glucocorticoid induction of viral reactivation proceeds via an HCF-1–GR mechanism in the absence of the viral IE activator VP16.IMPORTANCEBoHV-1 transcription is rapidly activated during stress-induced reactivation from latency. The immediate early transcription unit 1 (IEtu1) promoter is regulated by the GR via two GREs. The IEtu1 promoter regulates expression of two viral transcriptional regulatory proteins, infected cell proteins 0 and 4 (bICP0 and bICP4), and thus must be stimulated during reactivation. This study demonstrates that activation of the IEtu1 promoter by the synthetic corticosteroid dexamethasone requires HCF-1. Interestingly, the GRE sites, but not the IE enhancer core element (TAATGARAT), were required for HCF-1-mediated GR promoter activation. The GR and HCF-1 were recruited to the IEtu1 promoter in transfected and infected cells. Collectively, these studies indicate that HCF-1 is critical for GR activation of the viral IE genes and suggest that an HCF-1–GR complex can stimulate the IEtu1 promoter in the absence of the viral IE activator VP16.

scholarly journals The human cytomegalovirus US3 immediate-early protein lacking the putative transmembrane domain regulates gene expression

1993 ◽  
Vol 21 (12) ◽  
pp. 2931-2937 ◽  
Author(s):  
Daniel J. Tenney ◽  
Linda D. Santomenna ◽  
Karyn B. Goudie ◽  
Anamaris M. Colberg-Poley
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Transmembrane Domain ◽  
Immediate Early ◽  
Putative Transmembrane Domain ◽  
Early Protein

scholarly journals Lytic infection of permissive cells with human cytomegalovirus is regulated by an intrinsic ‘pre-immediate-early’ repression of viral gene expression mediated by histone post-translational modification

2009 ◽  
Vol 90 (10) ◽  
pp. 2364-2374 ◽  
Author(s):  
Ian J. Groves ◽  
Matthew B. Reeves ◽  
John H. Sinclair
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Chromatin Structure ◽  
Viral Gene Expression ◽  
Lytic Infection ◽  
Immediate Early ◽  
Late Gene ◽  
Viral Gene ◽  
Gene Promoters ◽  
Late Gene Expression

Human cytomegalovirus (HCMV) lytic gene expression occurs in a regulated cascade, initiated by expression of the viral major immediate-early (IE) proteins. Transcribed from the major IE promoter (MIEP), the major IE genes regulate viral early and late gene expression. This study found that a substantial proportion of infecting viral genomes became associated with histones immediately upon infection of permissive fibroblasts at low m.o.i. and these histones bore markers of repressed chromatin. As infection progressed, however, the viral MIEP became associated with histone marks, which correlate with the known transcriptional activity of the MIEP at IE time points. Interestingly, this chromatin-mediated repression of the MIEP at ‘pre-IE’ times of infection could be overcome by inhibition of histone deacetylases, as well as by infection at high m.o.i., and resulted in a temporal advance of the infection cycle by inducing premature viral early and late gene expression and DNA replication. As well as the MIEP, and consistent with previous observations, the viral early and late promoters were also initially associated with repressive chromatin. However, changes in histone modifications around these promoters also occurred as infection progressed, and this correlated with the known temporal regulation of the viral early and late gene expression cascade. These data argue that the chromatin structure of all classes of viral genes are initially repressed on infection of permissive cells and that the chromatin structure of HCMV gene promoters plays an important role in regulating the time course of viral gene expression during lytic infection.

scholarly journals Cwc23, an Essential J Protein Critical for Pre-mRNA Splicing with a Dispensable J Domain

2009 ◽  
Vol 30 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Chandan Sahi ◽  
Thomas Lee ◽  
Maki Inada ◽  
Jeffrey A. Pleiss ◽  
Elizabeth A. Craig
Keyword(s):  
Critical Role ◽  
Point Mutations ◽  
Mrna Splicing ◽  
Genetic Interactions ◽  
Loss Of Function ◽  
Partial Loss ◽  
J Proteins ◽  
J Domain ◽  
J Protein ◽  
Stimulation Of

ABSTRACT J proteins are structurally diverse, obligatory cochaperones of Hsp70s, each with a highly conserved J domain that plays a critical role in the stimulation of Hsp70's ATPase activity. The essential protein, Cwc23, is one of 13 J proteins found in the cytosol and/or nucleus of Saccharomyces cerevisiae. We report that a partial loss-of-function CWC23 mutant has severe, global defects in pre-mRNA splicing. This mutation leads to accumulation of the excised, lariat form of the intron, as well as unspliced pre-mRNA, suggesting a role for Cwc23 in spliceosome disassembly. Such a role is further supported by the observation that this mutation results in reduced interaction between Cwc23 and Ntr1 (SPP382), a known component of the disassembly pathway. However, Cwc23 is a very atypical J protein. Its J domain, although functional, is dispensable for both cell viability and pre-mRNA splicing. Nevertheless, strong genetic interactions were uncovered between point mutations encoding alterations in Cwc23's J domain and either Ntr1 or Prp43, a DExD/H-box helicase essential for spliceosome disassembly. These genetic interactions suggest that Hsp70-based chaperone machinery does play a role in the disassembly process. Cwc23 provides a unique example of a J protein; its partnership with Hsp70 plays an auxiliary, rather than a central, role in its essential cellular function.

scholarly journals Cellular and Viral Control over the Initial Events of Human Cytomegalovirus Experimental Latency in CD34+ Cells

2010 ◽  
Vol 84 (11) ◽  
pp. 5594-5604 ◽  
Author(s):  
Ryan T. Saffert ◽  
Rhiannon R. Penkert ◽  
Robert F. Kalejta
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Nuclear Body ◽  
Immune Defense ◽  
Lytic Infection ◽  
Viral Gene ◽  
Viral Control ◽  
Clinical Strains ◽  
Early Protein

ABSTRACT Human cytomegalovirus (HCMV) persists for the life of its host by establishing a latent infection. The identification of viral and cellular determinants of latency is the first step toward developing antiviral treatments that target and might clear or control the reservoir of latent virus. HCMV latency is established in CD34+ cells when expression of viral immediate early (IE) proteins that initiate lytic infection is silenced. Viral IE gene expression during lytic infection is controlled by a cellular intrinsic immune defense mediated by promyelocytic leukemia nuclear body (PML-NB) proteins such as Daxx and histone deacetylases (HDACs). This defense is inactivated at the start of lytic infection by the HCMV virion tegument protein pp71, which upon viral entry traffics to the nucleus and induces Daxx degradation. Here we show that a similar defense is present, active, and not neutralized during experimental latency in CD34+ cells infected in vitro because tegument-delivered pp71 remains in the cytoplasm. Artificial inactivation of this defense by HDAC inhibition or Daxx knockdown rescues viral IE gene expression upon infection of CD34+ cells with a laboratory-adapted viral strain but not with clinical strains. Interestingly, coinfection of CD34+ cells with clinical viral strains blocked the ability of an HDAC inhibitor to activate IE1 and early protein expression during infection with a laboratory-adapted strain. This suggests that in addition to the intrinsic defense, HCMV clinical strains contribute an HDAC-independent, trans-acting dominant means of control over viral gene expression during the early stages of experimental HCMV latency modeled in vitro in CD34+ cells.

scholarly journals Crystal Structure of the DNA-Binding Domain of Human Herpesvirus 6A Immediate Early Protein 2

2017 ◽  
Vol 91 (21) ◽  
Author(s):  
Mitsuhiro Nishimura ◽  
Junjie Wang ◽  
Aika Wakata ◽  
Kento Sakamoto ◽  
Yasuko Mori
Keyword(s):  
Gene Expression ◽  
Dna Binding ◽  
Binding Site ◽  
Human Herpesvirus ◽  
Binding Domain ◽  
Immediate Early ◽  
Dna Binding Domain ◽  
Factor Binding ◽  
Early Protein ◽  
Dna Binding Site

ABSTRACT Immediate early proteins of human herpesvirus 6A (HHV-6A) are expressed at the outset of lytic infection and thereby regulate viral gene expression. Immediate early protein 2 (IE2) of HHV-6A is a transactivator that drives a variety of promoters. The C-terminal region of HHV-6A IE2 is shared among IE2 homologs in betaherpesviruses and is involved in dimerization, DNA binding, and transcription factor binding. In this study, the structure of the IE2 C-terminal domain (IE2-CTD) was determined by X-ray crystallography at a resolution of 2.5 Å. IE2-CTD forms a homodimer stabilized by a β-barrel core with two interchanging long loops. Unexpectedly, the core structure resembles those of the gammaherpesvirus factors EBNA1 of Epstein-Barr virus and LANA of Kaposi sarcoma-associated herpesvirus, but the interchanging loops are longer in IE2-CTD and form helix-turn-helix (HTH)-like motifs at their tips. The HTH and surrounding α-helices form a structural feature specific to the IE2 group. The apparent DNA-binding site (based on structural similarity with EBNA1 and LANA) resides on the opposite side of the HTH-like motifs, surrounded by positive electrostatic potential. Mapping analysis of conserved residues on the three-dimensional structure delineated a potential factor-binding site adjacent to the expected DNA-binding site. The predicted bi- or tripartite functional sites indicate a role for IE2-CTD as an adapter connecting the promoter and transcriptional factors that drive gene expression. IMPORTANCE Human herpesvirus 6A (HHV-6A) and HHV-6B belong to betaherpesvirus subfamily. Both viruses establish lifelong latency after primary infection, and their reactivation poses a significant risk to immunocompromised patients. Immediate early protein 2 (IE2) of HHV-6A and HHV-6B is a transactivator that triggers viral replication and contains a DNA-binding domain shared with other betaherpesviruses such as human herpesvirus 7 and human cytomegalovirus. In this study, an atomic structure of the DNA-binding domain of HHV-6A IE2 was determined and analyzed, enabling a structure-based understanding of the functions of IE2, specifically DNA recognition and interaction with transcription factors. Unexpectedly, the dimeric core resembles the DNA-binding domain of transcription regulators from gammaherpesviruses, showing structural conservation as a DNA-binding domain but with its own unique structural features. These findings facilitate further characterization of this key viral transactivator.

scholarly journals The Human Cytomegalovirus 86-Kilodalton Major Immediate-Early Protein Interacts Physically and Functionally with Histone Acetyltransferase P/CAF

2000 ◽  
Vol 74 (16) ◽  
pp. 7230-7237 ◽  
Author(s):  
L. A. Bryant ◽  
P. Mixon ◽  
M. Davidson ◽  
A. J. Bannister ◽  
T. Kouzarides ◽  
...  
Keyword(s):  
Gene Expression ◽  
Human Cytomegalovirus ◽  
Histone Acetyltransferase ◽  
Early Gene ◽  
Immediate Early ◽  
Productive Infection ◽  
Early Protein ◽  
Cellular Genes ◽  
Immediate Early Proteins ◽  
Target Promoters

ABSTRACT The major immediate-early proteins of human cytomegalovirus (HCMV) play a pivotal role in controlling viral and cellular gene expression during productive infection. As well as negatively autoregulating its own promoter, the HCMV 86-kDa major immediate early protein (IE86) activates viral early gene expression and is known to be a promiscuous transcriptional regulator of cellular genes. IE86 appears to act as a multimodal transcription factor. It is able to bind directly to target promoters to activate transcription but is also able to bridge between upstream binding factors such as CREB/ATF and the basal transcription complex as well as interacting directly with general transcription factors such as TATA-binding protein and TFIIB. We now show that IE86 is also able to interact directly with histone acetyltransferases during infection. At least one of these factors is the histone acetyltransferase CBP-associated factor (P/CAF). Furthermore, we show that this interaction results in synergistic transactivation by IE86 of IE86-responsive promoters. Recruitment of such chromatin-remodeling factors to target promoters by IE86 may help explain the ability of this viral protein to act as a promiscuous transactivator of cellular genes.

scholarly journals Kaposi's Sarcoma-Associated Herpesvirus ORF66 Is Essential for Late Gene Expression and Virus Production via Interaction with ORF34

2019 ◽  
Vol 94 (2) ◽  
Author(s):  
Tadashi Watanabe ◽  
Mayu Nishimura ◽  
Taisuke Izumi ◽  
Kazushi Kuriyama ◽  
Yuki Iwaisako ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viral Replication ◽  
Kaposi's Sarcoma ◽  
Virus Production ◽  
Kaposi’S Sarcoma ◽  
Lytic Infection ◽  
Early Gene ◽  
Immediate Early ◽  
Late Gene ◽  
Late Gene Expression

ABSTRACT Kaposi’s sarcoma-associated herpesvirus (KSHV) is closely associated with B-cell and endothelial cell malignancies. After the initial infection, KSHV retains its viral genome in the nucleus of the host cell and establishes a lifelong latency. During lytic infection, KSHV-encoded lytic-related proteins are expressed in a sequential manner and are classified as immediate early, early, and late (L) gene transcripts. The transcriptional initiation of KSHV late genes is thought to require the complex formation of the viral preinitiation complex (vPIC), which may consist of at least 6 transcription factors (ORF18, -24, -30, -31, -34, and -66). However, the functional role of ORF66 in vPIC during KSHV replication remains largely unclear. Here, we generated ORF66-deficient KSHV using a bacterial artificial chromosome (BAC) system to evaluate its role during viral replication. While ORF66-deficient KSHV demonstrated mainly attenuated late gene expression and decreased virus production, viral DNA replication was unaffected. Chromatin immunoprecipitation analysis showed that ORF66 bound to the promoters of a late gene (K8.1) but did not bind to those of a latent gene (ORF72), an immediate early gene (ORF16), or an early gene (ORF46/47). Furthermore, we found that three highly conserved C-X-X-C sequences and a conserved leucine repeat in the C-terminal region of ORF66 were essential for the interaction with ORF34, the transcription of K8.1, and virus production. The interaction between ORF66 and ORF34 occurred in a zinc-dependent manner. Our data support a model in which ORF66 serves as a critical vPIC component to promote late viral gene expression and virus production. IMPORTANCE KSHV ORF66 is expressed during the early stages of lytic infection, and ORF66 and vPIC are thought to contribute significantly to late gene expression. However, the physiological importance of ORF66 in terms of vPIC formation remains poorly understood. Therefore, we generated an ORF66-deficient BAC clone and evaluated its viral replication. The results showed that ORF66 plays a critical role in virus production and the transcription of L genes. To our knowledge, this is the first report showing the function of ORF66 in virus replication using ORF66-deficient KSHV. We also clarified that ORF66 interacts with the transcription start site of the K8.1 gene, a late gene. Furthermore, we identified the ORF34-binding motifs in the ORF66 C terminus: three C-X-X-C sequences and a leucine-repeat sequence, which are highly conserved among beta- and gammaherpesviruses. Our study provides insights into the regulatory mechanisms of not only the late gene expression of KSHV but also those of other herpesviruses.

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