scholarly journals Novel Structure and Unexpected RNA-Binding Ability of the C-Terminal Domain of Herpes Simplex Virus 1 Tegument Protein UL21

2016 ◽  
Vol 90 (12) ◽  
pp. 5759-5769 ◽  
Author(s):  
Claire M. Metrick ◽  
Ekaterina E. Heldwein
Keyword(s):  
Crystal Structure ◽  
Herpes Simplex ◽  
Rna Binding ◽  
Tegument Protein ◽  
Functional Importance ◽  
Binding Ability ◽  
Herpes Simplex Virus 1 ◽  
3 Dimensional ◽  
Terminal Domain ◽  
Simplex Virus

ABSTRACTProteins forming the tegument layers of herpesviral virions mediate many essential processes in the viral replication cycle, yet few have been characterized in detail. UL21 is one such multifunctional tegument protein and is conserved among alphaherpesviruses. While UL21 has been implicated in many processes in viral replication, ranging from nuclear egress to virion morphogenesis to cell-cell spread, its precise roles remain unclear. Here we report the 2.7-Å crystal structure of the C-terminal domain of herpes simplex virus 1 (HSV-1) UL21 (UL21C), which has a unique α-helical fold resembling a dragonfly. Analysis of evolutionary conservation patterns and surface electrostatics pinpointed four regions of potential functional importance on the surface of UL21C to be pursued by mutagenesis. In combination with the previously determined structure of the N-terminal domain of UL21, the structure of UL21C provides a 3-dimensional framework for targeted exploration of the multiple roles of UL21 in the replication and pathogenesis of alphaherpesviruses. Additionally, we describe an unanticipated ability of UL21 to bind RNA, which may hint at a yet unexplored function.IMPORTANCEDue to the limited genomic coding capacity of viruses, viral proteins are often multifunctional, which makes them attractive antiviral targets. Such multifunctionality, however, complicates their study, which often involves constructing and characterizing null mutant viruses. Systematic exploration of these multifunctional proteins requires detailed road maps in the form of 3-dimensional structures. In this work, we determined the crystal structure of the C-terminal domain of UL21, a multifunctional tegument protein that is conserved among alphaherpesviruses. Structural analysis pinpointed surface areas of potential functional importance that provide a starting point for mutagenesis. In addition, the unexpected RNA-binding ability of UL21 may expand its functional repertoire. The structure of UL21C and the observation of its RNA-binding ability are the latest additions to the navigational chart that can guide the exploration of the multiple functions of UL21.

scholarly journals Crystal Structure of the N-Terminal Half of the Traffic Controller UL37 from Herpes Simplex Virus 1

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Andrea L. Koenigsberg ◽  
Ekaterina E. Heldwein
Keyword(s):  
Crystal Structure ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Pseudorabies Virus ◽  
Surface Region ◽  
Tegument Protein ◽  
Herpes Simplex Virus 1 ◽  
Tegument Proteins ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Inner tegument protein UL37 is conserved among all three subfamilies of herpesviruses. Studies of UL37 homologs from two alphaherpesviruses, herpes simplex virus 1 (HSV-1) and pseudorabies virus (PRV), have suggested that UL37 plays an essential albeit poorly defined role in intracellular capsid trafficking. At the same time, HSV and PRV homologs cannot be swapped, which suggests that in addition to a conserved function, UL37 homologs also have divergent virus-specific functions. Accurate dissection of UL37 functions requires detailed maps in the form of atomic-resolution structures. Previously, we reported the crystal structure of the N-terminal half of UL37 (UL37N) from PRV. Here, we report the crystal structure of HSV-1 UL37N. Comparison of the two structures reveals that UL37 homologs differ in their overall shapes, distributions of surface charges, and locations of projecting loops. In contrast, the previously identified R2 surface region is structurally conserved. We propose that within the N-terminal half of UL37, functional conservation is centered within the R2 surface region, whereas divergent structural elements pinpoint regions mediating virus-specific functions and may engage different binding partners. Together, the two structures can now serve as templates for a structure-guided exploration of both conserved and virus-specific functions of UL37. IMPORTANCE The ability to move efficiently within host cell cytoplasm is essential for replication in all viruses. It is especially important in the neuroinvasive alphaherpesviruses, such as human herpes simplex virus 1 (HSV-1), HSV-2, and veterinarian pseudorabies virus (PRV), that infect the peripheral nervous system and have to travel long distances along axons. Capsid movement in these viruses is controlled by capsid-associated tegument proteins, yet their specific roles have not yet been defined. Systematic exploration of the roles of tegument proteins in capsid trafficking requires detailed navigational charts in the form of their three-dimensional structures. Here, we determined the crystal structure of the N-terminal half of a conserved tegument protein, UL37, from HSV-1. This structure, along with our previously reported structure of the UL37 homolog from PRV, provides a much needed 3-dimensional template for the dissection of both conserved and virus-specific functions of UL37 in intracellular capsid trafficking.

scholarly journals Domain Interaction Studies of Herpes Simplex Virus 1 Tegument Protein UL16 Reveal Its Interaction with Mitochondria

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Pooja Chadha ◽  
Akua Sarfo ◽  
Dan Zhang ◽  
Thomas Abraham ◽  
Jillian Carmichael ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Tegument Protein ◽  
Herpes Simplex Virus 1 ◽  
Transfected Cells ◽  
Terminal Domain ◽  
Domain Interactions ◽  
Infected Cells ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT The UL16 tegument protein of herpes simplex virus 1 (HSV-1) is conserved among all herpesviruses and plays many roles during replication. This protein has an N-terminal domain (NTD) that has been shown to bind to several viral proteins, including UL11, VP22, and glycoprotein E, and these interactions are negatively regulated by a C-terminal domain (CTD). Thus, in pairwise transfections, UL16 binding is enabled only when the CTD is absent or altered. Based on these results, we hypothesized that direct interactions occur between the NTD and the CTD. Here we report that the separated and coexpressed functional domains of UL16 are mutually responsive to each other in transfected cells and form complexes that are stable enough to be captured in coimmunoprecipitation assays. Moreover, we found that the CTD can associate with itself. To our surprise, the CTD was also found to contain a novel and intrinsic ability to localize to specific spots on mitochondria in transfected cells. Subsequent analyses of HSV-infected cells by immunogold electron microscopy and live-cell confocal imaging revealed a population of UL16 that does not merely accumulate on mitochondria but in fact makes dynamic contacts with these organelles in a time-dependent manner. These findings suggest that the domain interactions of UL16 serve to regulate not just the interaction of this tegument protein with its viral binding partners but also its interactions with mitochondria. The purpose of this novel interaction remains to be determined. IMPORTANCE The HSV-1-encoded tegument protein UL16 is involved in multiple events of the virus replication cycle, ranging from virus assembly to cell-cell spread of the virus, and hence it can serve as an important drug target. Unfortunately, a lack of both structural and functional information limits our understanding of this protein. The discovery of domain interactions within UL16 and the novel ability of UL16 to interact with mitochondria in HSV-infected cells lays a foundational framework for future investigations aimed at deciphering the structure and function of not just UL16 of HSV-1 but also its homologs in other herpesviruses.

scholarly journals Crystal Structure of the Herpes Simplex Virus 1 DNA Polymerase

2006 ◽  
Vol 281 (26) ◽  
pp. 18193-18200 ◽  
Author(s):  
Shenping Liu ◽  
John D. Knafels ◽  
Jeanne S. Chang ◽  
Gregory A. Waszak ◽  
Eric T. Baldwin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Dna Polymerase ◽  
Herpes Simplex Virus 1 ◽  
Simplex Virus

scholarly journals ICP27 Phosphorylation Site Mutants Display Altered Functional Interactions with Cellular Export Factors Aly/REF and TAP/NXF1 but Are Able To Bind Herpes Simplex Virus 1 RNA

2009 ◽  
Vol 84 (5) ◽  
pp. 2212-2222 ◽  
Author(s):  
Kara A. Corbin-Lickfett ◽  
Santos Rojas ◽  
Ling Li ◽  
Melanie J. Cocco ◽  
Rozanne M. Sandri-Goldin
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Glutamic Acid ◽  
Protein Interactions ◽  
Rna Binding ◽  
Protein Localization ◽  
Phosphorylation Site ◽  
Herpes Simplex Virus 1 ◽  
N Terminus ◽  
Simplex Virus

ABSTRACT Herpes simplex virus 1 (HSV-1) protein ICP27 is a multifunctional regulatory protein that is phosphorylated. Phosphorylation can affect protein localization, protein interactions, and protein function. The major sites of ICP27 that are phosphorylated are serine residues 16 and 18, within a CK2 site adjacent to a leucine-rich region required for ICP27 export, and serine 114, within a PKA site in the nuclear localization signal. Viral mutants bearing serine-to-alanine or glutamic acid substitutions at these sites are defective in viral replication and gene expression. To determine which interactions of ICP27 are impaired, we analyzed the subcellular localization of ICP27 and its colocalization with cellular RNA export factors Aly/REF and TAP/NXF1. In cells infected with phosphorylation site mutants, ICP27 was confined to the nucleus even at very late times after infection. ICP27 did not colocalize with Aly/REF or TAP/NXF1, and overexpression of TAP/NXF1 did not promote the export of ICP27 to the cytoplasm. However, in vitro binding experiments showed that mutant ICP27 was able to bind to the same RNA substrates as the wild type. Nuclear magnetic resonance (NMR) analysis of the N terminus of ICP27 from amino acids 1 to 160, compared to mutants with triple substitutions to alanine or glutamic acid, showed that the mutations affected the overall conformation of the N terminus, such that mutant ICP27 was more flexible and unfolded. These results indicate that these changes in the structure of ICP27 altered in vivo protein interactions that occur in the N terminus but did not prevent RNA binding.

scholarly journals The Unusual Fold of Herpes Simplex Virus 1 UL21, a Multifunctional Tegument Protein

2014 ◽  
Vol 89 (5) ◽  
pp. 2979-2984 ◽  
Author(s):  
Claire M. Metrick ◽  
Pooja Chadha ◽  
Ekaterina E. Heldwein
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Multiple Roles ◽  
Tegument Protein ◽  
Potential Importance ◽  
Protein Fold ◽  
Herpes Simplex Virus 1 ◽  
Surface Patches ◽  
Evolutionarily Conserved ◽  
Simplex Virus

UL21 is a conserved protein in the tegument of alphaherpesviruses and has multiple important albeit poorly understood functions in viral replication and pathogenesis. To provide a roadmap for exploration of the multiple roles of UL21, we determined the crystal structure of its conserved N-terminal domain from herpes simplex virus 1 to 2.0-Å resolution, which revealed a novel sail-like protein fold. Evolutionarily conserved surface patches highlight residues of potential importance for future targeting by mutagenesis.

scholarly journals Evasion of the STING DNA-Sensing Pathway by VP11/12 of Herpes Simplex Virus 1

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Thibaut Deschamps ◽  
Maria Kalamvoki
Keyword(s):  
Innate Immunity ◽  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Tegument Protein ◽  
Type I ◽  
Herpes Simplex Virus 1 ◽  
Growth Defects ◽  
Foreign Dna ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT The stimulator of interferon (IFN) genes (STING) is a broad antimicrobial factor that restricts herpes simplex virus (HSV) by activating type I interferon and proinflammatory responses upon sensing of foreign DNA. UL46 is one of the most abundant tegument proteins of HSV-1, but a well-established function has yet to be found. We found that the HSV-1 UL46 protein interacts with and colocalizes with STING. A ΔUL46 virus displayed growth defects and activated innate immunity, but both effects were alleviated in STING knockdown cells. UL46 was also required for the inhibition of the 2′,3′-cyclic GMP-AMP (cGAMP)-dependent immune responses during infection. In cells expressing UL46, out of the context of the infection, innate immunity to a ΔICP0 virus was largely compromised, and that permitted ICP0-deficient mutants to replicate. The UL46-expressing cell lines also rescued the defects of the ΔUL46 virus and enhanced wild-type virus infection. The UL46-expressing cell lines did not activate interferon-stimulated gene (ISG) transcription following treatment with the noncanonical cyclic dinucleotide 2′,3′-cGAMP, suggesting that the STING pathway may be compromised. Indeed, we found that both proteins STING and IFI16 were eliminated in cells constitutively expressing UL46 and that the accumulation of their transcripts was blocked. Finally, we demonstrated that UL46 via its N terminus binds to STING and, via its C terminus, to TBK1. These interactions appear to modulate the functions of STING during HSV-1 infection. Taken together, our studies describe a novel function for one of the least-studied proteins of HSV, the tegument protein UL46, and that function involves the evasion of foreign DNA-sensing pathways. IMPORTANCE Herpes simplex virus 1 (HSV-1) afflicts 80% of the population worldwide, causing various diseases. After initial infection, the virus establishes latent reservoirs in sensory neurons and persists for life. Here we describe novel interactions between HSV-1 and the DNA sensor STING. We found that (i) HSV-1 tegument protein UL46 interacts with and colocalizes with STING; (ii) UL46 expressed out of the context of the infection blocks type I interferon triggered by STING stimuli, through the elimination of STING and of interferon-inducible protein 16 (IFI16); (iii) a ΔUL46 virus displayed growth defects, which were rescued in STING knockdown cells; (iv) the ΔUL46 virus failed to block innate immunity triggered by ligands of STING such as 2′,3′-cGAMP and also activated IFN-β and ISG expression; and (v) UL46 binds to both STING and TBK1 through different domains. We conclude that UL46 counteracts the actions of STING during HSV-1 infection.

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