scholarly journals Regulation of Poliovirus 3C Protease by the 2C Polypeptide

2004 ◽  
Vol 78 (17) ◽  
pp. 9243-9256 ◽  
Author(s):  
Rajeev Banerjee ◽  
Mary K. Weidman ◽  
Angela Echeverri ◽  
Pallob Kundu ◽  
Asim Dasgupta
Keyword(s):  
Cell Lines ◽  
Inhibitory Activity ◽  
Rna Binding ◽  
Rna Replication ◽  
Viral Rna ◽  
Physical Interaction ◽  
Viral Protease ◽  
Hela Cell Lines ◽  
Protease Inhibitory Activity

ABSTRACT Poliovirus-encoded nonstructural polypeptide 2C is a multifunctional protein that plays an important role in viral RNA replication. 2C interacts with both intracellular membranes and virus-specific RNAs and has ATPase and GTPase activities. Extensive computer analysis of the 2C sequence revealed that in addition to the known ATPase-, GTPase-, membrane-, and RNA-binding domains it also contains several “serpin” (serine protease inhibitor) motifs. We provide experimental evidence suggesting that 2C is indeed capable of regulating virus-encoded proteases. The purified 2C protein inhibits 3Cpro-catalyzed cleavage of cellular transcription factors at Q-G sites in vitro. It also inhibits cleavage of a viral precursor by the other viral protease, 2Apro. However, at least three cellular proteases appear not to be inhibited by 2C in vitro. The 2C-associated protease inhibitory activity can be depleted by anti-2C antibody. A physical interaction between 2C and His-tagged 3Cpro can be demonstrated in vitro by coimmunoprecipitation of 2C with anti-His antibody. Deletion analysis suggests that the 2C central and C-terminal domains that include several serpin motifs are important for 3Cpro-inhibitory activity. To examine the 2C protease inhibitory activity in vivo, stable HeLa cell lines were made that express 2C in an inducible fashion. Infection of 2C-expressing cells with poliovirus led to incomplete (or inefficient) processing of viral precursor polypeptides compared to control cell lines containing the vector alone. These results suggest that 2C can negatively regulate the viral protease 3Cpro. The possible role of the 2C protease inhibitory activity in viral RNA replication is discussed.

scholarly journals Long-Range RNA-RNA Interactions Circularize the Dengue Virus Genome

2005 ◽  
Vol 79 (11) ◽  
pp. 6631-6643 ◽  
Author(s):  
Diego E. Alvarez ◽  
María F. Lodeiro ◽  
Silvio J. Ludueña ◽  
Lía I. Pietrasanta ◽  
Andrea V. Gamarnik
Keyword(s):  
Dengue Virus ◽  
Rna Binding ◽  
Rna Replication ◽  
Virus Genome ◽  
Viral Rna ◽  
Physical Interaction ◽  
Virus Rna ◽  
Rna Elements ◽  
Rna Interaction

ABSTRACT Secondary and tertiary RNA structures present in viral RNA genomes play essential regulatory roles during translation, RNA replication, and assembly of new viral particles. In the case of flaviviruses, RNA-RNA interactions between the 5′ and 3′ ends of the genome have been proposed to be required for RNA replication. We found that two RNA elements present at the ends of the dengue virus genome interact in vitro with high affinity. Visualization of individual molecules by atomic force microscopy reveled that physical interaction between these RNA elements results in cyclization of the viral RNA. Using RNA binding assays, we found that the putative cyclization sequences, known as 5′ and 3′ CS, present in all mosquito-borne flaviviruses, were necessary but not sufficient for RNA-RNA interaction. Additional sequences present at the 5′ and 3′ untranslated regions of the viral RNA were also required for RNA-RNA complex formation. We named these sequences 5′ and 3′ UAR (upstream AUG region). In order to investigate the functional role of 5′-3′ UAR complementarity, these sequences were mutated either separately, to destroy base pairing, or simultaneously, to restore complementarity in the context of full-length dengue virus RNA. Nonviable viruses were recovered after transfection of dengue virus RNA carrying mutations either at the 5′ or 3′ UAR, while the RNA containing the compensatory mutations was able to replicate. Since sequence complementarity between the ends of the genome is required for dengue virus viability, we propose that cyclization of the RNA is a required conformation for viral replication.

scholarly journals CNOT4-Mediated Ubiquitination of Influenza A Virus Nucleoprotein Promotes Viral RNA Replication

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Yu-Chen Lin ◽  
King-Song Jeng ◽  
Michael M. C. Lai
Keyword(s):  
Influenza Virus ◽  
Influenza A Virus ◽  
Ubiquitin Ligase ◽  
Influenza A ◽  
Rna Binding ◽  
Rna Replication ◽  
Viral Rna ◽  
Mass Spectrometry Analysis ◽  
Positive Role

ABSTRACT Influenza A virus (IAV) RNA segments are individually packaged with viral nucleoprotein (NP) and RNA polymerases to form a viral ribonucleoprotein (vRNP) complex. We previously reported that NP is a monoubiquitinated protein which can be deubiquitinated by a cellular ubiquitin protease, USP11. In this study, we identified an E3 ubiquitin ligase, CNOT4 (Ccr4-Not transcription complex subunit 4), which can ubiquitinate NP. We found that the levels of viral RNA, protein, viral particles, and RNA polymerase activity in CNOT4 knockdown cells were lower than those in the control cells upon IAV infection. Conversely, overexpression of CNOT4 rescued viral RNP activity. In addition, CNOT4 interacted with the NP in the cell. An in vitro ubiquitination assay also showed that NP could be ubiquitinated by in vitro -translated CNOT4, but ubiquitination did not affect the protein stability of NP. Significantly, CNOT4 increased NP ubiquitination, whereas USP11 decreased it. Mass spectrometry analysis of ubiquitinated NP revealed multiple ubiquitination sites on the various lysine residues of NP. Three of these, K184, K227, and K273, are located on the RNA-binding groove of NP. Mutations of these sites to arginine reduced viral RNA replication. These results indicate that CNOT4 is a ubiquitin ligase of NP, and ubiquitination of NP plays a positive role in viral RNA replication. IMPORTANCE Influenza virus, particularly influenza A virus, causes severe and frequent outbreaks among human and avian species. Finding potential target sites for antiviral agents is of utmost importance from the public health point of view. We previously found that viral nucleoprotein (NP) is ubiquitinated, and ubiquitination enhances viral RNA replication. In this study, we found a cellular ubiquitin ligase, CNOT4, capable of ubiquitinating NP. The ubiquitination sites are scattered on the surface of the NP molecule, which is critical for RNA replication. CNOT4 and a ubiquitin protease, USP11, together regulate the extent of NP ubiquitination and thereby the efficiency of RNA replication. This study thus identifies a potential antiviral target site and reveals a novel posttranslational mechanism for regulating viral replication. This represents a novel finding in the literature of influenza virus research.

scholarly journals Proteomics Analysis of the Tombusvirus Replicase: Hsp70 Molecular Chaperone Is Associated with the Replicase and Enhances Viral RNA Replication

2006 ◽  
Vol 80 (5) ◽  
pp. 2162-2169 ◽  
Author(s):  
Saulius Serva ◽  
Peter D. Nagy
Keyword(s):  
Rna Binding ◽  
Rna Virus ◽  
Rna Replication ◽  
Viral Rna ◽  
Mass Spectrometry Analysis ◽  
Host Proteins ◽  
Two Dimensional Gel Electrophoresis ◽  
Viral Replicase

ABSTRACT Plus-strand RNA virus replication occurs via the assembly of viral replicase complexes involving multiple viral and host proteins. To identify host proteins present in the cucumber necrosis tombusvirus (CNV) replicase, we affinity purified functional viral replicase complexes from yeast. Mass spectrometry analysis of proteins resolved by two-dimensional gel electrophoresis revealed the presence of CNV p33 and p92 replicase proteins as well as four major host proteins in the CNV replicase. The host proteins included the Ssa1/2p molecular chaperones (yeast homologues of Hsp70 proteins), Tdh2/3p (glyceraldehyde-3-phosphate dehydrogenase, an RNA-binding protein), Pdc1p (pyruvate decarboxylase), and an unknown ∼35-kDa acidic protein. Copurification experiments demonstrated that Ssa1p bound to p33 replication protein in vivo, and surface plasmon resonance measurements with purified recombinant proteins confirmed this interaction in vitro. The double mutant strain (ssa1 ssa2) showed 75% reduction in viral RNA accumulation, whereas overexpression of either Ssa1p or Ssa2p stimulated viral RNA replication by approximately threefold. The activity of the purified CNV replicase correlated with viral RNA replication in the above-mentioned ssa1 ssa2 mutant and in the Ssa overexpression strains, suggesting that Ssa1/2p likely plays an important role in the assembly of the CNV replicase.

scholarly journals Interaction of the Influenza A Virus Nucleocapsid Protein with the Viral RNA Polymerase Potentiates Unprimed Viral RNA Replication

2008 ◽  
Vol 83 (1) ◽  
pp. 29-36 ◽  
Author(s):  
Laura L. Newcomb ◽  
Rei-Lin Kuo ◽  
Qiaozhen Ye ◽  
Yunyun Jiang ◽  
Yizhi Jane Tao ◽  
...  
Keyword(s):  
Influenza A Virus ◽  
Nucleocapsid Protein ◽  
Influenza A ◽  
Rna Binding ◽  
Direct Interaction ◽  
Rna Replication ◽  
Binding Activity ◽  
Viral Rna ◽  
Viral Polymerase

ABSTRACT The influenza A virus polymerase transcribes and replicates the eight virion RNA (vRNA) segments. Transcription is initiated with capped RNA primers excised from cellular pre-mRNAs by the intrinsic endonuclease of the viral polymerase. Viral RNA replication occurs in two steps: first a full-length copy of vRNA is made, termed cRNA, and then this cRNA is copied to produce vRNA. The synthesis of cRNAs and vRNAs is initiated without a primer, in contrast to the initiation of viral mRNA synthesis, and requires the viral nucleocapsid protein (NP). The mechanism of unprimed viral RNA replication is poorly understood. To elucidate this mechanism, we used purified recombinant influenza virus polymerase complexes and NP to establish an in vitro system that catalyzes the unprimed synthesis of cRNA and vRNA using 50-nucleotide-long RNA templates. The purified viral polymerase and NP are sufficient for catalyzing this RNA synthesis without a primer, suggesting that host cell factors are not required. We used this purified in vitro replication system to demonstrate that the RNA-binding activity of NP is not required for the unprimed synthesis of cRNA and vRNA. This result rules out two models that postulate that the RNA-binding activity of NP mediates the switch from capped RNA-primed transcription to unprimed viral RNA replication. Because we showed that NP lacking RNA-binding activity binds directly to the viral polymerase, it is likely that a direct interaction between NP and the viral polymerase results in a modification of the polymerase in favor of unprimed initiation.

Effect of black seeds (Nigella sativa) volatile oil on the cervical cancer: In vitro study, on Hela cell lines

2019 ◽  
Vol 7 (4) ◽  
pp. 91-96
Author(s):  
Isra'a Al-sobhi ◽  
◽  
Rawan Al-Ghabban ◽  
Soad Shaker Ali ◽  
Jehan Al-Amri ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Hela Cell ◽  
Cell Lines ◽  
Nigella Sativa ◽  
In Vitro Study ◽  
Volatile Oil ◽  
Vitro Study ◽  
Hela Cell Lines ◽  
Black Seeds

1'-methylspiro[indoline-3,4'-piperidine] Derivatives: Design, Synthesis, Molecular Docking and Anti-tumor Activity Studies

2020 ◽  
Vol 17 ◽  
Author(s):  
Junjian Li ◽  
Lianbao Ye ◽  
Yuanyuan Wang ◽  
Ying Liu ◽  
Xiaobao Jin ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Cell Lines ◽  
Active Sites ◽  
Biological Activities ◽  
Significant Inhibition ◽  
Alkaline Condition ◽  
Discovery Studio ◽  
Hela Cell Lines ◽  
Antiproliferative Activities

Background: Spirocyclic indoline compounds widely exist in numerous natural products with good biological activities and some drug molecules in many aspects. In recent years, it has attracted extensive attention as potent anti-tumor agents in the fields of pharmacology and chemistry. Objective: In this study, we focused on designing and synthesizing a set of novel 1'-H-spiro[indole-3,4'-piperidine] derivatives, which were evaluated by preliminary bioactivity experiment in vitro and molecular docking. Method: The key intermediate 1'-methylspiro[indoline-3,4'-piperidine] (B4) reacted with benzenesulfonyl chloride with different substituents under alkaline condition to obtain its sulfonyl derivatives (B5-B10). We evaluated their antiproliferative activities against A549, BEL-7402 and HeLa cells by MTT assay. We performed the CDOCKER module in Discovery Studio 2.5.5 software for molecular modeling of compound B5, and investigated the binding of compound B5 with the target proteins from PDB database. Results: The results indicated that compounds B4-B10 exhibited good antiproliferative activities against the above three types of cells, in which compound B5 with chloride atom as electron-withdrawing substituent on a phenyl ring showed the highest potency against BEL-7402 cells (IC50=30.03±0.43 μg/mL). By binging of the prominent bioactive compound B5 to CDK, c-Met, EGFR protein crystals, The binding energy of B5 with these three types receptors are -44.3583 kcal/mol, - 38.3292 kcal/mol, -33.3653 kcal/mol respectively. Conclusion: Six 1'-methylspiro[indoline-3,4'-piperidine] derivatives were synthesized and evaluated against BEL-7402, A- 549, HeLa cell lines. Compound B5 showed significant inhibition on BEL-7402 cell lines. Molecular docking revealed that B5 showed good affinity by the good fitting between B5 and these three targets with amino acid residues in active sites which encourage us to conduct further evaluation such as the kinase experiment.

New Ferrocene Compounds as Selective Cyclooxygenase (COX-2) Inhibitors: Design, Synthesis, Cytotoxicity and Enzyme-inhibitory Activity

2018 ◽  
Vol 18 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Shabnam Farzaneh ◽  
Elnaz Zeinalzadeh ◽  
Bahram Daraei ◽  
Soraya Shahhosseini ◽  
Afshin Zarghi
Keyword(s):  
Cell Lines ◽  
Inhibitory Activity ◽  
Fibroblast Cell ◽  
Breast Cancer Cell Lines ◽  
Ferrocene Derivatives ◽  
Cox 2 ◽  
Cytotoxicity Effects ◽  
Cox 2 Inhibitors ◽  
Mcf 7

Background: Due to the astonishing properties of ferrocene and its derivatives, it has a broad application in diverse areas. Numerous ferrocene derivatives demonstrated anti-proliferative activity. Also COX-2, as a key isoenzyme for production of prostaglandins, is frequently overexpressed in various cancers. It is now recognized that COX-2 over expression promotes tumorigenic functions which can be suppressed by COX-2 inhibitors, a phenomenon useful for the preventing of tumor progression. The combination of COX-2 inhibitors with other anti-cancer or cancer prevention drugs may reduce their side effects in future cancer prevention and treatment. Objective: Owing to high anticancer potential of ferrocene derivatives and considerable COX-2 inhibitory and cytotoxicity effects of our previously synthesized chalcones, we decided to incorporate the ferrocenyl moiety into appropriate COX-2 inhibitor chalcone based scaffold, to evaluate COX-2 inhibitory activity as well as anticancer activities. Methods: Chalcones were synthesized via clasien-schmidt condensation of methylsulfonyl aldehyde and acetyl ferrocene. Further different amines with solvent free and ultra sound condition were reacted with chalcones to have different 1-ferrocenyl-3-amino carbonyl compounds. Docking study was carried out with Auto Dock vina software. All the newly-synthesized compounds were evaluated for their cyclooxygenase-2 (COX-2) inhibitory activity using chemiluminescent enzyme assays as well as cytotoxicity activity against MCF-7 and T47D and fibroblast cell lines by MTT assay. Results: In vitro COX-1/COX-2 inhibition studies demonstrated that all compounds were selective inhibitors of the COX-2 isozyme with IC50 values in the highly potent 0.05-0.12 µM range, and COX-2 selectivity indexes (SI) in the 148.3-313.7 range. These results indicated that either potency or selectivity of COX-2 inhibitory activity was affected by the nature and size of the substituents on C-3 of propane-1-one. Also anti-proliferative and toxicity activities of synthesized compounds against breast cancer cell lines MCF-7 and T47D and fibroblast cell lines showed that the synthesized compounds had mild to moderate cytotoxicity against MCT7 and T47D breast cancer cell lines at 10 µM concentration. In vitro COX-1/COX-2 inhibition studies and anticancer activity against MCF-7, identified 1-ferrocenyl-3-(4-methylsulfonylphenyl) propen-1-one as a potent compound (IC50 COX-2 = 0.05 µM, MCF-7: % inhibition (at concentration of 10 µM) = 32.7%), and also 1-ferrocenyl-3- (propan-1-amine)-3-(4-methylsulfonylphenyl) propan-1-one showed the most selectivity on COX-2 inhibition (selectivity index= 313.7). Conclusion: A novel group of ferrocene compounds, possessing a methyl sulfonyl COX-2 pharmacophore were synthesized to investigate the effect of different substituents on selectivity and potency of COX-2 inhibitory activity and their cytotoxicity effects. This study indicates that 1-ferrocenyl-3-amino carbonyl compounds having ferrocene motif and methyl sulfonyl COX-2 pharmacophore is a suitable scaffold to design COX-2 inhibitors and anti-cancer agents.

scholarly journals Andrographis paniculata (Burm. F.) Wall. Ex Nees, Andrographolide, and Andrographolide Analogues as SARS-CoV-2 Antivirals? A Rapid Review

2021 ◽  
Vol 16 (5) ◽  
pp. 1934578X2110166
Author(s):  
Xin Yi Lim ◽  
Janice Sue Wen Chan ◽  
Terence Yew Chin Tan ◽  
Bee Ping Teh ◽  
Mohd Ridzuan Mohd Abd Razak ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
In Silico ◽  
Rna Binding ◽  
Symptomatic Relief ◽  
Andrographis Paniculata ◽  
Spike Protein ◽  
Rapid Review ◽  
In Silico Studies

Drug repurposing is commonly employed in the search for potential therapeutic agents. Andrographis paniculata, a medicinal plant commonly used for symptomatic relief of the common cold, and its phytoconstituent andrographolide, have been repeatedly identified as potential antivirals against SARS-CoV-2. In light of new evidence emerging since the onset of the COVID-19 pandemic, this rapid review was conducted to identify and evaluate the current SARS-CoV-2 antiviral evidence for A. paniculata, andrographolide, and andrographolide analogs. A systematic search and screen strategy of electronic databases and gray literature was undertaken to identify relevant primary articles. One target-based in vitro study reported the 3CLpro inhibitory activity of andrographolide as being no better than disulfiram. Another Vero cell-based study reported potential SARS-CoV-2 inhibitory activity for both andrographolide and A. paniculata extract. Eleven in silico studies predicted the binding of andrographolide and its analogs to several key antiviral targets of SARS-CoV-2 including the spike protein-ACE-2 receptor complex, spike protein, ACE-2 receptor, RdRp, 3CLpro, PLpro, and N-protein RNA-binding domain. In conclusion, in silico and in vitro studies collectively suggest multi-pathway targeting SARS-CoV-2 antiviral properties of andrographolide and its analogs, but in vivo data are needed to support these predictions.

scholarly journals The cytotoxic activity of pine needles ethanolic extract of Pinus merkusii on HeLa cell lines

2021 ◽  
Vol 33 ◽  
pp. 03001
Author(s):  
Annise Proboningrat ◽  
Amaq Fadholly ◽  
Sri Agus Sudjarwo ◽  
Fedik Abdul Rantam ◽  
Agung Budianto Achmad
Keyword(s):  
Cytotoxic Activity ◽  
Cell Lines ◽  
Anticancer Agents ◽  
Anticancer Agent ◽  
Ethanolic Extract ◽  
In Vitro Cytotoxicity ◽  
Hela Cell Lines ◽  
Cytotoxicity Assessment ◽  
Pinus Merkusii

Several efforts have been made to discover new anticancer agents based on natural ingredients. Meanwhile, previous studies have shown that different Pine genus species exhibit cytotoxic activity against various types of cancer cells. This plant is rich in phenolic compounds, especially procyanidins, flavonoids, and phenolic acids. Therefore, this study aims to investigate the in vitro cytotoxicity of Pinus merkusii needles extract on HeLa cancer cell lines. The cytotoxicity assessment was measured using MTT assay and expressed as IC50 value. The results showed that the ethanolic extract poses a dose and time-dependent cytotoxic activity with an IC50 value of 542.5 µg/ml at 48 hours of incubation. Based on this result, Pinus merkusii needles’ ethanolic extract has the potential of a novel candidate for an anticancer agent.

scholarly journals Distinct Poly(rC) Binding Protein KH Domain Determinants for Poliovirus Translation Initiation and Viral RNA Replication

2002 ◽  
Vol 76 (23) ◽  
pp. 12008-12022 ◽  
Author(s):  
Brandon L. Walter ◽  
Todd B. Parsley ◽  
Ellie Ehrenfeld ◽  
Bert L. Semler
Keyword(s):  
Translation Initiation ◽  
Rna Synthesis ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Replication ◽  
Viral Rna ◽  
Host Protein ◽  
Loop Structure ◽  
Stem Loop ◽  
Stem Loop Structure

ABSTRACT The limited coding capacity of picornavirus genomic RNAs necessitates utilization of host cell factors in the completion of an infectious cycle. One host protein that plays a role in both translation initiation and viral RNA synthesis is poly(rC) binding protein 2 (PCBP2). For picornavirus RNAs containing type I internal ribosome entry site (IRES) elements, PCBP2 binds the major stem-loop structure (stem-loop IV) in the IRES and is essential for translation initiation. Additionally, the binding of PCBP2 to the 5′-terminal stem-loop structure (stem-loop I or cloverleaf) in concert with viral protein 3CD is required for initiation of RNA synthesis directed by poliovirus replication complexes. PCBP1, a highly homologous isoform of PCBP2, binds to poliovirus stem-loop I with an affinity similar to that of PCBP2; however, PCBP1 has reduced affinity for stem-loop IV. Using a dicistronic poliovirus RNA, we were able to functionally uncouple translation and RNA replication in PCBP-depleted extracts. Our results demonstrate that PCBP1 rescues RNA replication but is not able to rescue translation initiation. We have also generated mutated versions of PCBP2 containing site-directed lesions in each of the three RNA-binding domains. Specific defects in RNA binding to either stem-loop I and/or stem-loop IV suggest that these domains may have differential functions in translation and RNA replication. These predictions were confirmed in functional assays that allow separation of RNA replication activities from translation. Our data have implications for differential picornavirus template utilization during viral translation and RNA replication and suggest that specific PCBP2 domains may have distinct roles in these activities.

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