scholarly journals Crystal structures of ORFV125 provide insight into orf virus-mediated inhibition of apoptosis

2020 ◽  
Vol 477 (23) ◽  
pp. 4527-4541 ◽  
Author(s):  
Chathura D. Suraweera ◽  
Mark G. Hinds ◽  
Marc Kvansakul
Keyword(s):  
Host Cell ◽  
Crystal Structures ◽  
B Cell Lymphoma ◽  
Orf Virus ◽  
Structural Basis ◽  
Inhibitory Protein ◽  
Affinity Ligand ◽  
Host Cell Apoptosis ◽  
Mechanistic Basis ◽  
Binding Groove

Premature apoptosis of cells is a strategy utilized by multicellular organisms to counter microbial threats. Orf virus (ORFV) is a large double-stranded DNA virus belonging to the poxviridae. ORFV encodes for an apoptosis inhibitory protein ORFV125 homologous to B-cell lymphoma 2 or Bcl-2 family proteins, which has been shown to inhibit host cell encoded pro-apoptotic Bcl-2 proteins. However, the structural basis of apoptosis inhibition by ORFV125 remains to be clarified. We show that ORFV125 is able to bind to a range of peptides spanning the BH3 motif of human pro-apoptotic Bcl-2 proteins including Bax, Bak, Puma and Hrk with modest to weak affinity. We then determined the crystal structures of ORFV125 alone as well as bound to the highest affinity ligand Bax BH3 motif. ORFV125 adopts a globular Bcl-2 fold comprising 7 α-helices, and utilizes the canonical Bcl-2 binding groove to engage pro-apoptotic host cell Bcl-2 proteins. In contrast with a previously predicted structure, ORFV125 adopts a domain-swapped dimeric topology, where the α1 helix from one protomer is swapped into a neighbouring unit. Furthermore, ORFV125 differs from the conserved architecture of the Bcl-2 binding groove and instead of α3 helix forming one of the binding groove walls, ORFV125 utilizes an extended α2 helix that comprises the equivalent region of helix α3. This results in a subtle variation of previously observed dimeric Bcl-2 architectures in other poxvirus and human encoded Bcl-2 proteins. Overall, our results provide a structural and mechanistic basis for orf virus-mediated inhibition of host cell apoptosis.

scholarly journals Structural insight into tanapoxvirus mediated inhibition of apoptosis

2020 ◽  
Author(s):  
Chathura D. Suraweera ◽  
Mohd Ishtiaq Anasir ◽  
Srishti Chugh ◽  
Airah Javorsky ◽  
Rachael E. Impey ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Host Cell ◽  
Inhibitory Protein ◽  
Double Stranded Dna ◽  
Host Cell Apoptosis ◽  
Mechanistic Basis ◽  
Binding Groove ◽  
Multicellular Organisms ◽  
Oligomeric Forms ◽  
Insight Into

AbstractPremature programmed cell death or apoptosis of cells is a strategy utilized by multicellular organisms to counter microbial threats. Tanapoxvirus (TANV) is a large double-stranded DNA virus belonging to the poxviridae that causes mild Monkeypox-like infections in humans and primates. TANV encodes for a putative apoptosis inhibitory protein 16L. We show that TANV16L is able to bind to a range of peptides spanning the BH3 motif of human pro-apoptotic Bcl-2 proteins, and is able to counter growth arrest of yeast induced by human Bak and Bax. We then determined the crystal structures of TANV16L bound to three identified interactors, Bax, Bim and Puma BH3. TANV16L adopts a globular Bcl-2 fold comprising 7 α-helices, and utilizes the canonical Bcl-2 binding groove to engage pro-apoptotic host cell Bcl-2 proteins. Unexpectedly, TANV16L is able to adopt both a monomeric as well as a domain-swapped dimeric topology where the α1 helix from one protomer is swapped into a neighbouring unit. Despite adopting two different oligomeric forms, the canonical ligand binding groove in TANV16L remains unchanged from monomer to domain-swapped dimer. Our results provide a structural and mechanistic basis for tanapoxvirus mediated inhibition of host cell apoptosis, and reveal the capacity of Bcl-2 proteins to adopt differential oligomeric states whilst maintaining the canonical ligand binding groove in an unchanged state.

scholarly journals Structural Investigation of Orf Virus Bcl-2 Homolog ORFV125 Interactions with BH3-Motifs from BH3-Only Proteins Puma and Hrk

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1374
Author(s):  
Chathura D. Suraweera ◽  
Mark G. Hinds ◽  
Marc Kvansakul
Keyword(s):  
Cell Death ◽  
Structural Investigation ◽  
Potent Inhibitor ◽  
Host Cells ◽  
Orf Virus ◽  
Structural Basis ◽  
Signalling Pathways ◽  
Ionic Interaction ◽  
Host Cell Apoptosis ◽  
Binding Groove

Numerous viruses have evolved sophisticated countermeasures to hijack the early programmed cell death of host cells in response to infection, including the use of proteins homologous in sequence or structure to Bcl-2. Orf virus, a member of the parapoxviridae, encodes for the Bcl-2 homolog ORFV125, a potent inhibitor of Bcl-2-mediated apoptosis in the host. ORFV125 acts by directly engaging host proapoptotic Bcl-2 proteins including Bak and Bax as well as the BH3-only proteins Hrk and Puma. Here, we determined the crystal structures of ORFV125 bound to the BH3 motif of proapoptotic proteins Puma and Hrk. The structures reveal that ORFV125 engages proapoptotic BH3 motif peptides using the canonical ligand binding groove. An Arg located in the structurally equivalent BH1 region of ORFV125 forms an ionic interaction with the conserved Asp in the BH3 motif in a manner that mimics the canonical ionic interaction seen in host Bcl-2:BH3 motif complexes. These findings provide a structural basis for Orf virus-mediated inhibition of host cell apoptosis and reveal the flexibility of virus encoded Bcl-2 proteins to mimic key interactions from endogenous host signalling pathways.

scholarly journals Comparative Analyses of Transcriptional Profiles in Mouse Organs Using a Pneumonic Plague Model after Infection with Wild-TypeYersinia pestisCO92 and Its Braun Lipoprotein Mutant

2009 ◽  
Vol 2009 ◽  
pp. 1-16 ◽  
Author(s):  
Cristi L. Galindo ◽  
Scott T. Moen ◽  
Elena V. Kozlova ◽  
Jian Sha ◽  
Harold R. Garner ◽  
...  
Keyword(s):  
Gene Expression ◽  
Host Cell ◽  
Apoptotic Cell ◽  
Cytokine Signaling ◽  
Infection Model ◽  
Transcriptional Responses ◽  
Pneumonic Plague ◽  
Transcriptional Profiles ◽  
Host Cell Apoptosis ◽  
Mechanistic Basis

We employed Murine GeneChips to delineate the global transcriptional profiles of the livers, lungs, and spleens in a mouse pneumonic plague infection model with wild-type (WT)Y. pestisCO92 and its Braun lipoprotein (Δlpp) mutant with reduced virulence. These organs showed differential transcriptional responses to infection with WTY. pestis, but the overall host functional processes affected were similar across all three tissues. Gene expression alterations were found in inflammation, cytokine signaling, and apoptotic cell death-associated genes. Comparison of WT andΔlppmutant-infected mice indicated significant overlap in lipopolysaccharide- (LPS-) associated gene expression, but the absence of Lpp perturbed host cell signaling at critical regulatory junctions resulting in altered immune response and possibly host cell apoptosis. We generated a putative signaling pathway including major inflammatory components that could account for the synergistic action of LPS and Lpp and provided the mechanistic basis of attenuation caused by deletion of thelppgene fromY. pestisin a mouse model of pneumonic plague.

scholarly journals Crystal structures of the sheeppoxvirus encoded inhibitor of apoptosis SPPV14 bound to Hrk and Bax BH3 peptides

2020 ◽  
Author(s):  
Chathura D. Suraweera ◽  
Denis R. Burton ◽  
Mark G. Hinds ◽  
Marc Kvansakul
Keyword(s):  
Crystal Structures ◽  
Viral Infections ◽  
Structural Basis ◽  
Ionic Interaction ◽  
Apoptosis Inhibition ◽  
Programmed Death ◽  
Infected Cells ◽  
Binding Groove ◽  
Almost All ◽  
Multicellular Organisms

AbstractProgrammed death of infected cells is used by multicellular organisms to counter viral infections. Sheeppoxvirus encodes for SPPV14, a potent inhibitor of Bcl-2 mediated apoptosis. We reveal the structural basis of apoptosis inhibition by determining crystal structures of SPPV14 bound to BH3 motifs of proapoptotic Bax and Hrk. The structures show that SPPV14 engages BH3 peptides using the canonical ligand binding groove. Unexpectedly, Arg84 from SPPV14 forms an ionic interaction with the conserved Asp in the BH3 motif in a manner that replaces the canonical ionic interaction seen in almost all host Bcl-2:BH3 motif complexes. These results reveal the flexibility of virus encoded Bcl-2 proteins to mimic key interactions from endogenous host signalling pathways to retain BH3-binding and pro-survival functionality.

scholarly journals The Hypothetical Inclusion Membrane Protein CPSIT_0846 Regulates Mitochondrial-Mediated Host Cell Apoptosis via the ERK/JNK Signaling Pathway

2021 ◽  
Vol 11 ◽  
Author(s):  
Ting Tang ◽  
Haiying Wu ◽  
Xi Chen ◽  
Li Chen ◽  
Luyao Liu ◽  
...  
Keyword(s):  
Host Cell ◽  
Signaling Pathway ◽  
Hela Cells ◽  
Cell Apoptosis ◽  
B Cell Lymphoma ◽  
Inclusion Membrane ◽  
Jnk Signaling ◽  
Amino Terminal ◽  
Host Cell Apoptosis ◽  
Jnk Signaling Pathway

Chlamydia psittaci is an important zoonotic factor associated with human and animal atypical pneumonia. Resisting host cell apoptosis is central to sustaining Chlamydia infection in vivo. Chlamydia can secrete inclusion membrane proteins (Incs) that play important roles in their development cycle and pathogenesis. CPSIT_0846 is an Inc protein in C. psittaci identified by our team in previous work. In the current study, we investigated the regulatory role of CPSIT_0846 in HeLa cell apoptosis, and explored potential mechanisms. The results showed that HeLa cells treated with CPSIT_0846 contained fewer apoptotic bodies and exhibited a lower apoptotic rate than untreated cells either with Hoechst 33258 fluorescence staining or flow cytometry with or without induction by staurosporine (STS). CPSIT_0846 could increase the phosphorylation of the extracellular signal-regulated kinases 1/2 (ERK1/2) or stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathways, and the Bcl-2 associated X protein (Bax)/B cell lymphoma 2 (Bcl-2) ratio, levels of cleaved caspase-3/9 and cleaved Poly-ADP-ribose polymerase (PARP) were significantly up-regulated following inhibition of ERK1/2 or SAPK/JNK pathways with U0126 or SP600125. After carbonyl cyanide 3-chlorophenylhydrazone (CCCP) treatment, the mitochondrial membrane potential (MMP) of cells was significantly decreased in control group, but stable in the CPSIT_0846 treated one, and less cytochrome c (Cyt.c) was released into the cytoplasm. Inhibition of the ERK1/2 or SAPK/JNK pathway significantly decreased the JC-1 red-green fluorescence signal, and promoted Cyt.c discharge into the cytoplasm in HeLa cells treated with CPSIT_0846. In conclusion, CPSIT_0846 can regulate mitochondrial pathway-mediated apoptosis in HeLa cells by activating the ERK/JNK signaling pathway.

Structural basis ofDeerpox virus-mediated inhibition of apoptosis

2015 ◽  
Vol 71 (8) ◽  
pp. 1593-1603 ◽  
Author(s):  
Denis R. Burton ◽  
Sofia Caria ◽  
Bevan Marshall ◽  
Michele Barry ◽  
Marc Kvansakul
Keyword(s):  
Structural Analysis ◽  
Ligand Binding ◽  
Structural Basis ◽  
Inhibitor Of Apoptosis ◽  
Defence Mechanism ◽  
Partial Obstruction ◽  
Host Cell Apoptosis ◽  
Infected Cells ◽  
Binding Groove ◽  
Innate Defence

Apoptosis is a key innate defence mechanism to eliminate virally infected cells. To counteract premature host-cell apoptosis, poxviruses have evolved numerous molecular strategies, including the use of Bcl-2 proteins, to ensure their own survival. Here, it is reported that theDeerpox virusinhibitor of apoptosis, DPV022, only engages a highly restricted set of death-inducing Bcl-2 proteins, including Bim, Bax and Bak, with modest affinities. Structural analysis reveals that DPV022 adopts a Bcl-2 fold with a dimeric domain-swapped topology and binds pro-death Bcl-2 proteinsviatwo conserved ligand-binding grooves found on opposite sides of the dimer. Structures of DPV022 bound to Bim, Bak and Bax BH3 domains reveal that a partial obstruction of the binding groove is likely to be responsible for the modest affinities of DPV022 for BH3 domains. These findings reveal that domain-swapped dimeric Bcl-2 folds are not unusual and may be found more widely in viruses. Furthermore, the modest affinities of DPV022 for pro-death Bcl-2 proteins suggest that two distinct classes of anti-apoptotic viral Bcl-2 proteins exist: those that are monomeric and tightly bind a range of death-inducing Bcl-2 proteins, and others such as DPV022 that are dimeric and only bind a very limited number of death-inducing Bcl-2 proteins with modest affinities.

Crystal structures of Magnaporthe oryzae trehalose-6-phosphate synthase (MoTps1) suggest a model for catalytic process of Tps1

2019 ◽  
Vol 476 (21) ◽  
pp. 3227-3240 ◽  
Author(s):  
Shanshan Wang ◽  
Yanxiang Zhao ◽  
Long Yi ◽  
Minghe Shen ◽  
Chao Wang ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Conformational Changes ◽  
Magnaporthe Oryzae ◽  
Structural Information ◽  
Complex Structure ◽  
Critical Role ◽  
Catalytic Process ◽  
Structural Basis ◽  
Salt Bridges ◽  
Terminal Domain

Trehalose-6-phosphate (T6P) synthase (Tps1) catalyzes the formation of T6P from UDP-glucose (UDPG) (or GDPG, etc.) and glucose-6-phosphate (G6P), and structural basis of this process has not been well studied. MoTps1 (Magnaporthe oryzae Tps1) plays a critical role in carbon and nitrogen metabolism, but its structural information is unknown. Here we present the crystal structures of MoTps1 apo, binary (with UDPG) and ternary (with UDPG/G6P or UDP/T6P) complexes. MoTps1 consists of two modified Rossmann-fold domains and a catalytic center in-between. Unlike Escherichia coli OtsA (EcOtsA, the Tps1 of E. coli), MoTps1 exists as a mixture of monomer, dimer, and oligomer in solution. Inter-chain salt bridges, which are not fully conserved in EcOtsA, play primary roles in MoTps1 oligomerization. Binding of UDPG by MoTps1 C-terminal domain modifies the substrate pocket of MoTps1. In the MoTps1 ternary complex structure, UDP and T6P, the products of UDPG and G6P, are detected, and substantial conformational rearrangements of N-terminal domain, including structural reshuffling (β3–β4 loop to α0 helix) and movement of a ‘shift region' towards the catalytic centre, are observed. These conformational changes render MoTps1 to a ‘closed' state compared with its ‘open' state in apo or UDPG complex structures. By solving the EcOtsA apo structure, we confirmed that similar ligand binding induced conformational changes also exist in EcOtsA, although no structural reshuffling involved. Based on our research and previous studies, we present a model for the catalytic process of Tps1. Our research provides novel information on MoTps1, Tps1 family, and structure-based antifungal drug design.

scholarly journals Poxviral Strategies to Overcome Host Cell Apoptosis

Pathogens ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 6
Author(s):  
Chathura D. Suraweera ◽  
Mark G. Hinds ◽  
Marc Kvansakul
Keyword(s):  
Viral Infections ◽  
B Cell Lymphoma ◽  
Intrinsic Apoptosis ◽  
Host Cell Apoptosis ◽  
Successful Infection ◽  
Infected Cells ◽  
Host Virus Interactions ◽  
Almost All ◽  
Virus Interactions ◽  
Multicellular Organisms

Apoptosis is a form of cellular suicide initiated either via extracellular (extrinsic apoptosis) or intracellular (intrinsic apoptosis) cues. This form of programmed cell death plays a crucial role in development and tissue homeostasis in multicellular organisms and its dysregulation is an underlying cause for many diseases. Intrinsic apoptosis is regulated by members of the evolutionarily conserved B-cell lymphoma-2 (Bcl-2) family, a family that consists of pro- and anti-apoptotic members. Bcl-2 genes have also been assimilated by numerous viruses including pox viruses, in particular the sub-family of chordopoxviridae, a group of viruses known to infect almost all vertebrates. The viral Bcl-2 proteins are virulence factors and aid the evasion of host immune defenses by mimicking the activity of their cellular counterparts. Viral Bcl-2 genes have proved essential for the survival of virus infected cells and structural studies have shown that though they often share very little sequence identity with their cellular counterparts, they have near-identical 3D structures. However, their mechanisms of action are varied. In this review, we examine the structural biology, molecular interactions, and detailed mechanism of action of poxvirus encoded apoptosis inhibitors and how they impact on host–virus interactions to ultimately enable successful infection and propagation of viral infections.

scholarly journals Structural and mechanistic basis for translation inhibition by macrolide and ketolide antibiotics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bertrand Beckert ◽  
Elodie C. Leroy ◽  
Shanmugapriya Sothiselvam ◽  
Lars V. Bock ◽  
Maxim S. Svetlov ◽  
...  
Keyword(s):  
Antibiotic Resistance Genes ◽  
Structural Basis ◽  
Sequence Motifs ◽  
Specific Sequence ◽  
Bacterial Ribosome ◽  
Translational Arrest ◽  
Exit Tunnel ◽  
Mechanistic Basis ◽  
Dynamics Simulations ◽  
Context Specific

AbstractMacrolides and ketolides comprise a family of clinically important antibiotics that inhibit protein synthesis by binding within the exit tunnel of the bacterial ribosome. While these antibiotics are known to interrupt translation at specific sequence motifs, with ketolides predominantly stalling at Arg/Lys-X-Arg/Lys motifs and macrolides displaying a broader specificity, a structural basis for their context-specific action has been lacking. Here, we present structures of ribosomes arrested during the synthesis of an Arg-Leu-Arg sequence by the macrolide erythromycin (ERY) and the ketolide telithromycin (TEL). Together with deep mutagenesis and molecular dynamics simulations, the structures reveal how ERY and TEL interplay with the Arg-Leu-Arg motif to induce translational arrest and illuminate the basis for the less stringent sequence-specific action of ERY over TEL. Because programmed stalling at the Arg/Lys-X-Arg/Lys motifs is used to activate expression of antibiotic resistance genes, our study also provides important insights for future development of improved macrolide antibiotics.

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