scholarly journals Mapping the Nonstructural Protein Interaction Network of Porcine Reproductive and Respiratory Syndrome Virus

2018 ◽  
Vol 92 (24) ◽  
Author(s):  
Jiangwei Song ◽  
Yuanyuan Liu ◽  
Peng Gao ◽  
Yunhao Hu ◽  
Yue Chai ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Rna Virus ◽  
Nonstructural Protein ◽  
Transmembrane Proteins ◽  
Interaction Network ◽  
Host Cells ◽  
Respiratory Syndrome Virus ◽  
Reading Frame ◽  
Interaction Map ◽  
Transcription Complexes

ABSTRACTPorcine reproductive and respiratory syndrome virus (PRRSV) is a positive-stranded RNA virus belonging to the familyArteriviridae. Synthesis of the viral RNA is directed by replication/transcription complexes (RTC) that are mainly composed of a network of PRRSV nonstructural proteins (nsps) and likely cellular proteins. Here, we mapped the interaction network among PRRSV nsps by using yeast two-hybrid screening in conjunction with coimmunoprecipitation (co-IP) and cotransfection assays. We identified a total of 24 novel interactions and found that the interactions were centered on open reading frame 1b (ORF1b)-encoded nsps that were mainly connected by the transmembrane proteins nsp2, nsp3, and nsp5. Interestingly, the interactions of the core enzymes nsp9 and nsp10 with transmembrane proteins did not occur in a straightforward manner, as they worked in the co-IP assay but were poorly capable of finding each other within intact mammalian cells. Further proof that they can interact within cells required the engineering of N-terminal truncations of both nsp9 and nsp10. However, despite the poor colocalization relationship in cotransfected cells, both nsp9 and nsp10 came together with membrane proteins (e.g., nsp2) at the viral replication and transcription complexes (RTC) in PRRSV-infected cells. Thus, our results indicate the existence of a complex interaction network among PRRSV nsps and raise the possibility that the recruitment of key replicase proteins to membrane-associated nsps may involve some regulatory mechanisms during infection.IMPORTANCESynthesis of PRRSV RNAs within host cells depends on the efficient and correct assembly of RTC that takes places on modified intracellular membranes. As an important step toward dissecting this poorly understood event, we investigated the interaction network among PRRSV nsps. Our studies established a comprehensive interaction map for PRRSV nsps and revealed important players within the network. The results also highlight the likely existence of a regulated recruitment of the PRRSV core enzymes nsp9 and nsp10 to viral membrane nsps during PRRSV RTC assembly.

scholarly journals Identification of an intramolecular switch that controls the interaction of the helicase nsp10 with the membrane-associated nsp12 of porcine reproductive and respiratory syndrome virus

2021 ◽  
Author(s):  
Yunhao Hu ◽  
Purui Ke ◽  
Peng Gao ◽  
Yongning Zhang ◽  
Lei Zhou ◽  
...  
Keyword(s):  
Rna Synthesis ◽  
Reverse Genetics ◽  
Nonstructural Protein ◽  
Interaction Network ◽  
Single Amino Acid ◽  
Respiratory Syndrome Virus ◽  
Subgenomic Rna ◽  
Linker Region ◽  
Transcription Complexes ◽  
Rna Accumulation

A critical step in replication of positive-stranded RNA viruses is the assembly of replication and transcription complexes (RTC). We have recently mapped the nonstructural protein (nsp) interaction network of porcine reproductive and respiratory syndrome virus (PRRSV) and provided evidence by truncation mutagenesis that the recruitment of viral core replicase enzymes (nsp9 and nsp10) to membrane proteins (nsp2, nsp3, nsp5 and nsp12) is subject to regulation. Here, we went further to discover an intramolecular switch within the helicase nsp10 that controls its interaction with the membrane-associated protein nsp12. Deletion of nsp10 linker region aa.124-133 connecting the domain 1B to 1A led to complete re-localization and co-localization in the cells co-expressing nsp12. Moreover, single amino acid substitutions (e.g., nsp10 E131A and I132A) were sufficient to enable the nsp10-nsp12 interaction. Further proof came from membrane floatation assays that revealed a clear movement of nsp10 mutants, but not WT nsp10, towards the top of sucrose gradients in the presence of nsp12. Interestingly, the same mutations were not able to activate the nsp10-nsp2/3 interaction, suggesting a differential requirement for conformation. Reverse genetics analysis showed that PRRSV mutants carrying the single substitutions were not viable and defective of subgenomic RNA (sg RNA) accumulation. Together, our results provide strong evidence for a regulated interaction between nsp10 and nsp12 and suggest an essential role for an orchestrated RTC assembly in sg RNA synthesis. IMPORTANCE Assembly of replication and transcription complexes (RTC) is a limiting step for viral RNA synthesis. The PRRSV RTC macromolecular complexes are comprised of mainly viral nonstructural replicase proteins (nsps), but how they come together remains elusive. We previously showed that viral helicase nsp10 interacts nsp12 in a regulated manner by truncation mutagenesis. Here we revealed that the interaction is controlled by single residues within the domain linker region of nsp10. Moreover, the activation mutations leads to defect in viral sg RNA synthesis. Our results provide important insight into the mechanisms of PRRSV RTC assembly and regulation of viral sg RNA synthesis.

Increase of SARS-CoV 3CL peptidase activity due to macromolecular crowding effects in the milieu composition

2010 ◽  
Vol 391 (12) ◽  
Author(s):  
Debora N. Okamoto ◽  
Lilian C.G. Oliveira ◽  
Marcia Y. Kondo ◽  
Maria H.S. Cezari ◽  
Zoltán Szeltner ◽  
...  
Keyword(s):  
Rna Virus ◽  
Antiviral Agents ◽  
Fine Tuning ◽  
Host Cells ◽  
Respiratory Syndrome Virus ◽  
Peptidase Activity ◽  
Buffer Solutions ◽  
Tuning Mechanism ◽  
Positive Strand Rna Virus ◽  
Positive Strand Rna

Abstract The 3C-like peptidase of the severe acute respiratory syndrome virus (SARS-CoV) is strictly required for viral replication, thus being a potential target for the development of antiviral agents. In contrast to monomeric picornavirus 3C peptidases, SARS-CoV 3CLpro exists in equilibrium between the monomer and dimer forms in solution, and only the dimer is proteolytically active in dilute buffer solutions. In this study, the increase of SARS-CoV 3CLpro peptidase activity in presence of kosmotropic salts and crowding agents is described. The activation followed the Hofmeister series of anions, with two orders of magnitude enhancement in the presence of Na2SO4, whereas the crowding agents polyethylene glycol and bovine serum albumin increased the hydrolytic rate up to 3 times. Kinetic determinations of the monomer dimer dissociation constant (K d) indicated that activation was a result of a more active dimer, without significant changes in K d values. The activation was found to be independent of substrate length and was derived from both k cat increase and K m decrease. The viral peptidase activation described here could be related to the crowded intracellular environment and indicates a further fine-tuning mechanism for biological control, particularly in the microenvironment of the vesicles that are induced in host cells during positive strand RNA virus infection.

scholarly journals Nodamura Virus Nonstructural Protein B2 Can Enhance Viral RNA Accumulation in both Mammalian and Insect Cells

2004 ◽  
Vol 78 (12) ◽  
pp. 6698-6704 ◽  
Author(s):  
Kyle L. Johnson ◽  
B. Duane Price ◽  
Lance D. Eckerle ◽  
L. Andrew Ball
Keyword(s):  
Rna Interference ◽  
Cell Lines ◽  
Nonstructural Protein ◽  
Viral Rna ◽  
Host Cells ◽  
Flock House Virus ◽  
Nonstructural Proteins ◽  
Reading Frame ◽  
Rna Accumulation ◽  
Nodamura Virus

ABSTRACT During infection of both vertebrate and invertebrate cell lines, the alphanodavirus Nodamura virus (NoV) expresses two nonstructural proteins of different lengths from the B2 open reading frame. The functions of these proteins have yet to be determined, but B2 of the related Flock House virus suppresses RNA interference both in Drosophila cells and in transgenic plants. To examine whether the NoV B2 proteins had similar functions, we compared the replication of wild-type NoV RNA with that of mutants unable to make the B2 proteins. We observed a defect in the accumulation of mutant viral RNA that varied in extent from negligible in some cell lines (e.g., baby hamster kidney cells) to severe in others (e.g., human HeLa and Drosophila DL-1 cells). These results are consistent with the notion that the NoV B2 proteins act to circumvent an innate antiviral response such as RNA interference that differs in efficacy among different host cells.

scholarly journals MicroRNA-7 Inhibits Rotavirus Replication by Targeting Viral NSP5 In Vivo and In Vitro

Viruses ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 209 ◽  
Author(s):  
Yan Zhou ◽  
Linlin Chen ◽  
Jing Du ◽  
Xiaoqing Hu ◽  
Yuping Xie ◽  
...  
Keyword(s):  
Rna Virus ◽  
Nonstructural Protein ◽  
Antiviral Effect ◽  
Host Cells ◽  
Mice Model ◽  
Live Attenuated Vaccine ◽  
Severe Diarrhea ◽  
Regulation Method

Rotavirus (RV) is the major causes of severe diarrhea in infants and young children under five years of age. There are no effective drugs for the treatment of rotavirus in addition to preventive live attenuated vaccine. Recent evidence demonstrates that microRNAs (miRNAs) can affect RNA virus replication. However, the antiviral effect of miRNAs during rotavirus replication are largely unknown. Here, we determined that miR-7 is upregulated during RV replication and that it targets the RV NSP5 (Nonstructural protein 5). Results suggested that miR-7 affected viroplasm formation and inhibited RV replication by down-regulating RV NSP5 expression. Up-regulation of miR-7 expression is a common regulation method of different G-type RV-infected host cells. Then, we further revealed the antiviral effect of miR-7 in diarrhea suckling mice model. MiR-7 is able to inhibit rotavirus replication in vitro and in vivo. These data provide that understanding the role of cellular miR-7 during rotaviral replication may help in the identification of novel therapeutic small RNA molecule drug for anti-rotavirus.

scholarly journals Orsay δ Protein Is Required for Nonlytic Viral Egress

2018 ◽  
Vol 92 (14) ◽  
Author(s):  
Wang Yuan ◽  
Ying Zhou ◽  
Yanlin Fan ◽  
Yizhi J. Tao ◽  
Weiwei Zhong
Keyword(s):  
Rna Virus ◽  
Nonstructural Protein ◽  
Mutant Virus ◽  
Host Cells ◽  
Apical Surface ◽  
Content Type ◽  
C Elegans ◽  
Apical Side ◽  
Orsay Virus

ABSTRACTNonenveloped gastrointestinal viruses, such as human rotavirus, can exit infected cells from the apical surface without cell lysis. The mechanism of such nonlytic exit is poorly understood. The nonenveloped Orsay virus is an RNA virus infecting the intestine cells of the nematodeCaenorhabditis elegans. Dye staining results suggested that Orsay virus exits from the intestine of infected worms in a nonlytic manner. Therefore, the Orsay virus-C. eleganssystem provides an excellentin vivomodel to study viral exit. The Orsay virus genome encodes three proteins: RNA-dependent RNA polymerase, capsid protein (CP), and a nonstructural protein, δ. δ can also be expressed as a structural CP-δ fusion. We generated an ATG-to-CTG mutant virus that had a normal CP-δ fusion but could not produce free δ due to the lack of the start codon. This mutant virus showed a viral exit defect without obvious phenotypes in other steps of viral infection, suggesting that δ is involved in viral exit. Ectopically expressed free δ localized near the apical membrane of intestine cells inC. elegansand colocalized with ACT-5, an intestine-specific actin that is a component of the terminal web. Orsay virus infection rearranged ACT-5 apical localization. Reduction of the ACT-5 level via RNA interference (RNAi) significantly exacerbated the viral exit defect of the δ mutant virus, suggesting that δ and ACT-5 functionally interact to promote Orsay virus exit. Together, these data support a model in which the viral δ protein interacts with the actin network at the apical side of host intestine cells to mediate the polarized, nonlytic egress of Orsay virus.IMPORTANCEAn important step of the viral life cycle is how viruses exit from host cells to spread to other cells. Certain nonenveloped viruses can exit cultured cells in nonlytic ways; however, such nonlytic exit has not been demonstratedin vivo. In addition, it is not clear how such nonlytic exit is achieved mechanisticallyin vivo. Orsay virus is a nonenveloped RNA virus that infects the intestine cells of the nematodeC. elegans. It is currently the only virus known to naturally infectC. elegans. Using thisin vivomodel, we show that the δ protein encoded by Orsay virus facilitates the nonlytic exit of the virus, possibly by interacting with host actin on the apical side of worm intestine cells.

scholarly journals Virus-Specific mRNA Capping Enzyme Encoded by Hepatitis E Virus

2001 ◽  
Vol 75 (14) ◽  
pp. 6249-6255 ◽  
Author(s):  
Julia Magden ◽  
Naokazu Takeda ◽  
Tiancheng Li ◽  
Petri Auvinen ◽  
Tero Ahola ◽  
...  
Keyword(s):  
Mosaic Virus ◽  
Hepatitis E Virus ◽  
Rna Virus ◽  
Nonstructural Protein ◽  
Hepatitis E ◽  
Brome Mosaic Virus ◽  
Reading Frame ◽  
Animal Virus ◽  
Capping Enzyme ◽  
Positive Strand Rna

ABSTRACT Hepatitis E virus (HEV), a positive-strand RNA virus, is an important causative agent of waterborne hepatitis. Expression of cDNA (encoding amino acids 1 to 979 of HEV nonstructural open reading frame 1) in insect cells resulted in synthesis of a 110-kDa protein (P110), a fraction of which was proteolytically processed to an 80-kDa protein. P110 was tightly bound to cytoplasmic membranes, from which it could be released by detergents. Immunopurified P110 catalyzed transfer of a methyl group from S-adenosylmethionine (AdoMet) to GTP and GDP to yield m7GTP or m7GDP. GMP, GpppG, and GpppA were poor substrates for the P110 methyltransferase. There was no evidence for further methylation of m7GTP when it was used as a substrate for the methyltransferase. P110 was also a guanylyltransferase, which formed a covalent complex, P110-m7GMP, in the presence of AdoMet and GTP, because radioactivity from both [α-32P]GTP and [3H-methyl]AdoMet was found in the covalent guanylate complex. Since both methyltransferase and guanylyltransferase reactions are strictly virus specific, they should offer optimal targets for development of antiviral drugs. Cap analogs such as m7GTP, m7GDP, et2m7GMP, and m2et7GMP inhibited the methyltransferase reaction. HEV P110 capping enzyme has similar properties to the methyltransferase and guanylyltransferase of alphavirus nsP1, tobacco mosaic virus P126, brome mosaic virus replicase protein 1a, and bamboo mosaic virus (a potexvirus) nonstructural protein, indicating there is a common evolutionary origin of these distantly related plant and animal virus families.

scholarly journals Structural comparison of CD163 SRCR5 from different species sheds some light on its involvement in porcine reproductive and respiratory syndrome virus-2 infection in vitro

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Hongfang Ma ◽  
Rui Li ◽  
Longguang Jiang ◽  
Songlin Qiao ◽  
Xin-xin Chen ◽  
...  
Keyword(s):  
Scavenger Receptor ◽  
Host Cells ◽  
Respiratory Syndrome Virus ◽  
Swine Industry ◽  
Prrs Virus ◽  
Rich Domain ◽  
Serious Disease ◽  
The One ◽  
And Control

AbstractPorcine reproductive and respiratory syndrome (PRRS) is a serious disease burdening global swine industry. Infection by its etiological agent, PRRS virus (PRRSV), shows a highly restricted tropism of host cells and has been demonstrated to be mediated by an essential scavenger receptor (SR) CD163. CD163 fifth SR cysteine-rich domain (SRCR5) is further proven to play a crucial role during viral infection. Despite intense research, the involvement of CD163 SRCR5 in PRRSV infection remains to be elucidated. In the current study, we prepared recombinant monkey CD163 (moCD163) SRCR5 and human CD163-like homolog (hCD163L1) SRCR8, and determined their crystal structures. After comparison with the previously reported crystal structure of porcine CD163 (pCD163) SRCR5, these structures showed almost identical structural folds but significantly different surface electrostatic potentials. Based on these differences, we carried out mutational research to identify that the charged residue at position 534 in association with the one at position 561 were important for PRRSV-2 infection in vitro. Altogether the current work sheds some light on CD163-mediated PRRSV-2 infection and deepens our understanding of the viral pathogenesis, which will provide clues for prevention and control of PRRS.

scholarly journals Polypurine Reverse-Hoogsteen Hairpins as a Tool for Exon Skipping at the Genomic Level in Mammalian Cells

2021 ◽  
Vol 22 (7) ◽  
pp. 3784
Author(s):  
Véronique Noé ◽  
Carlos J. Ciudad
Keyword(s):  
Dna Sequencing ◽  
Rare Diseases ◽  
Mammalian Cells ◽  
Mrna Level ◽  
Exon Skipping ◽  
Selective Medium ◽  
Rt Pcr ◽  
Exon 2 ◽  
Reading Frame ◽  
Additional Exon

Therapeutic strategies for rare diseases based on exon skipping are aimed at mediating the elimination of mutated exons and restoring the reading frame of the affected protein. We explored the capability of polypurine reverse-Hoogsteen hairpins (PPRHs) to cause exon skipping in NB6 cells carrying a duplication of exon 2 of the DHFR gene that causes a frameshift abolishing DHFR activity. Methods: Different editing PPRHs were designed and transfected in NB6 cells followed by incubation in a DHFR-selective medium lacking hypoxanthine and thymidine. Surviving colonies were analyzed by DNA sequencing, RT-PCR, Western blotting and DHFR enzymatic activity. Results: Transfection of editing PPRHs originated colonies in the DHFR-selective medium. DNA sequencing results proved that the DHFR sequence in all these colonies corresponded to the wildtype sequence with just one copy of exon 2. In the edited colonies, the skipping of the additional exon was confirmed at the mRNA level, the DHFR protein was restored, and it showed high levels of DHFR activity. Conclusions: Editing-PPRHs are able to cause exon skipping at the DNA level and could be applied as a possible therapeutic tool for rare diseases.

scholarly journals Native Structure-Based Peptides as Potential Protein–Protein Interaction Inhibitors of SARS-CoV-2 Spike Protein and Human ACE2 Receptor

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2157
Author(s):  
Norbert Odolczyk ◽  
Ewa Marzec ◽  
Maria Winiewska-Szajewska ◽  
Jarosław Poznański ◽  
Piotr Zielenkiewicz
Keyword(s):  
Drug Development ◽  
Protein Interactions ◽  
Rna Virus ◽  
Antiviral Drug ◽  
Host Protein ◽  
Host Cells ◽  
Cell Surface Receptor ◽  
Short Peptides ◽  
Virus Protein ◽  
Positive Strand Rna

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a positive-strand RNA virus that causes severe respiratory syndrome in humans, which is now referred to as coronavirus disease 2019 (COVID-19). Since December 2019, the new pathogen has rapidly spread globally, with over 65 million cases reported to the beginning of December 2020, including over 1.5 million deaths. Unfortunately, currently, there is no specific and effective treatment for COVID-19. As SARS-CoV-2 relies on its spike proteins (S) to bind to a host cell-surface receptor angiotensin-converting enzyme-2(ACE2), and this interaction is proved to be responsible for entering a virus into host cells, it makes an ideal target for antiviral drug development. In this work, we design three very short peptides based on the ACE2 sequence/structure fragments, which may effectively bind to the receptor-binding domain (RBD) of S protein and may, in turn, disrupt the important virus-host protein–protein interactions, blocking early steps of SARS-CoV-2 infection. Two of our peptides bind to virus protein with affinity in nanomolar range, and as very short peptides have great potential for drug development.

scholarly journals Role for nsP2 Proteins in the Cessation of Alphavirus Minus-Strand Synthesis by Host Cells

2006 ◽  
Vol 80 (1) ◽  
pp. 360-371 ◽  
Author(s):  
Dorothea L. Sawicki ◽  
Silvia Perri ◽  
John M. Polo ◽  
Stanley G. Sawicki
Keyword(s):  
Host Response ◽  
Rna Synthesis ◽  
Late Phase ◽  
Host Cells ◽  
Minus Strand ◽  
Wild Type ◽  
Persistent Infections ◽  
Infected Cells ◽  
Replicative Intermediates ◽  
Transcription Complexes

ABSTRACT In order to establish nonlytic persistent infections (PI) of BHK cells, replicons derived from Sindbis (SIN) and Semliki Forest (SFV) viruses have mutations in nsP2. Five different nsP2 PI replicons were compared to wild-type (wt) SIN, SFV, and wt nsPs SIN replicons. Replicon PI BHK21 cells had viral RNA synthesis rates that were less than 5% of those of the wt virus and ∼10% or less of those of SIN wt replicon-infected cells, and, in contrast to wt virus and replicons containing wt nsP2, all showed a phenotype of continuous minus-strand synthesis and of unstable, mature replication/transcription complexes (RC+) that are active in plus-strand synthesis. Minus-strand synthesis and incorporation of [3H]uridine into replicative intermediates differed among PI replicons, depending on the location of the mutation in nsP2. Minus-strand synthesis by PI cells appeared normal; it was dependent on continuous P123 and P1234 polyprotein synthesis and ceased when protein synthesis was inhibited. The failure by the PI replicons to shut off minus-strand synthesis was not due to some defect in the PI cells but rather was due to the loss of some function in the mutated nsP2. This was demonstrated by showing that superinfection of PI cells with wt SFV triggered the shutdown of minus-strand synthesis, which we believe is a host response to infection with alphaviruses. Together, the results indicate alphavirus nsP2 functions to engage the host response to infection and activate a switch from the early-to-late phase. The loss of this function leads to continuous viral minus-strand synthesis and the production of unstable RC+.

Sign in / Sign up

Export Citation Format

Share Document