scholarly journals Cleavage targets and the D-arginine-based inhibitors of the West Nile virus NS3 processing proteinase

2005 ◽  
Vol 393 (2) ◽  
pp. 503-511 ◽  
Author(s):  
Sergey A. Shiryaev ◽  
Boris I. Ratnikov ◽  
Alexei V. Chekanov ◽  
Sergey Sikora ◽  
Dmitri V. Rozanov ◽  
...  

Mosquito-borne WNV (West Nile virus) is an emerging global threat. The NS3 proteinase, which is essential for the proteolytic processing of the viral polyprotein precursor, is a promising drug target. We have isolated and biochemically characterized the recombinant, highly active NS3 proteinase. We have determined that the NS3 proteinase functions in a manner that is distantly similar to furin in cleaving the peptide and protein substrates. We determined that aprotinin and D-arginine-based 9–12-mer peptides are potent inhibitors of WNV NS3 with Ki values of 26 nM and 1 nM respectively. Consistent with the essential role of NS3 activity in the life cycle of WNV and with the sensitivity of NS3 activity to the D-arginine-based peptides, we showed that nona-D-Arg-NH2 reduced WNV infection in primary neurons. We have also shown that myelin basic protein, a deficiency of which is linked to neurological abnormalities of the brain, is sensitive to NS3 proteolysis in vitro and therefore this protein represents a convenient test substrate for the studies of NS3. A three-dimensional model of WNV NS3 that we created may provide a structural guidance and a rationale for the subsequent design of fine-tuned inhibitors. Overall, our findings represent a foundation for in-depth mechanistic and structural studies as well as for the design of novel and efficient inhibitors of WNV NS3.

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Olanrewaju Ayodeji Durojaye ◽  
Nkwachukwu Oziamara Okoro ◽  
Arome Solomon Odiba

Abstract Background The novel coronavirus SARS-CoV-2 is currently a global threat to health and economies. Therapeutics and vaccines are in rapid development; however, none of these therapeutics are considered as absolute cure, and the potential to mutate makes it necessary to find therapeutics that target a highly conserved regions of the viral structure. Results In this study, we characterized an essential but poorly understood coronavirus accessory X4 protein, a core and stable component of the SARS-CoV family. Sequence analysis shows a conserved ~ 90% identity between the SARS-CoV-2 and previously characterized X4 protein in the database. QMEAN Z score of the model protein shows a value of around 0.5, within the acceptable range 0–1. A MolProbity score of 2.96 was obtained for the model protein and indicates a good quality model. The model has Ramachandran values of φ = − 57o and ψ = − 47o for α-helices and values of φ = − 130o and ψ = + 140o for twisted sheets. Conclusions The protein data obtained from this study provides robust information for further in vitro and in vivo experiment, targeted at devising therapeutics against the virus. Phylogenetic analysis further supports previous evidence that the SARS-CoV-2 is positioned with the SL-CoVZC45, BtRs-BetaCoV/YN2018B and the RS4231 Bat SARS-like corona viruses.


2018 ◽  
Vol 12 (10) ◽  
pp. e0006886 ◽  
Author(s):  
Agathe M. G. Colmant ◽  
Sonja Hall-Mendelin ◽  
Scott A. Ritchie ◽  
Helle Bielefeldt-Ohmann ◽  
Jessica J. Harrison ◽  
...  

2017 ◽  
Vol 61 (11) ◽  
Author(s):  
Estela Escribano-Romero ◽  
Nereida Jiménez de Oya ◽  
Esteban Domingo ◽  
Juan Carlos Saiz

ABSTRACT Favipiravir is an antiviral agent effective against several RNA viruses. The drug has been shown to protect mice against experimental infection with a lethal dose of West Nile virus (WNV), a mosquito-borne flavivirus responsible for outbreaks of meningitis and encephalitis for which no antiviral therapy has been licensed; however, the mechanism of action of the drug is still not well understood. Here, we describe the potent in vitro antiviral activity of favipiravir against WNV, showing that it decreases virus-specific infectivity and drives the virus to extinction. Two passages of WNV in the presence of 1 mM favipiravir—a concentration that is more than 10-fold lower than its 50% cytotoxic concentration (CC50)—resulted in a significant increase in mutation frequency in the mutant spectrum and in a bias toward A→G and G→A transitions relative to the population passaged in the absence of the drug. These data, together with the fact that the drug is already licensed in Japan against influenza virus and in a clinical trial against Ebola virus, point to favipiravir as a promising antiviral agent to fight medically relevant flaviviral infections, such as that caused by WNV.


2021 ◽  
Vol 13 ◽  
pp. 175883592110598
Author(s):  
Inken Flörkemeier ◽  
Tamara N. Steinhauer ◽  
Nina Hedemann ◽  
Magnus Ölander ◽  
Per Artursson ◽  
...  

Background: Ovarian cancer (OvCa) constitutes a rare and highly aggressive malignancy and is one of the most lethal of all gynaecologic neoplasms. Due to chemotherapy resistance and treatment limitations because of side effects, OvCa is still not sufficiently treatable. Hence, new drugs for OvCa therapy such as P8-D6 with promising antitumour properties have a high clinical need. The benzo[ c]phenanthridine P8-D6 is an effective inductor of apoptosis by acting as a dual topoisomerase I/II inhibitor. Methods: In the present study, the effectiveness of P8-D6 on OvCa was investigated in vitro. In various OvCa cell lines and ex vivo primary cells, the apoptosis induction compared with standard therapeutic agents was determined in two-dimensional monolayers. Expanded by three-dimensional and co-culture, the P8-D6 treated cells were examined for changes in cytotoxicity, apoptosis rate and membrane integrity via scanning electron microscopy (SEM). Likewise, the effects of P8-D6 on non-cancer human ovarian surface epithelial cells and primary human hepatocytes were determined. Results: This study shows a significant P8-D6-induced increase in apoptosis and cytotoxicity in OvCa cells which surpasses the efficacy of well-established drugs like cisplatin or the topoisomerase inhibitors etoposide and topotecan. Non-cancer cells were affected only slightly by P8-D6. Moreover, no hepatotoxic effect in in vitro studies was detected. Conclusion: P8-D6 is a strong and rapid inductor of apoptosis and might be a novel treatment option for OvCa therapy.


2001 ◽  
Vol 82 (4) ◽  
pp. 765-773 ◽  
Author(s):  
Andres Merits ◽  
Lidia Vasiljeva ◽  
Tero Ahola ◽  
Leevi Kääriäinen ◽  
Petri Auvinen

The RNA replicase proteins of Semliki Forest virus (SFV) are translated as a P1234 polyprotein precursor that contains two putative autoproteases. Point mutations introduced into the predicted active sites of both proteases nsP2 (P2) and nsP4 (P4), separately or in combination, completely abolished virus replication in mammalian cells. The effects of these mutations on polyprotein processing were studied by in vitro translation and by expression of wild-type polyproteins P1234, P123, P23, P34 and their mutated counterparts in insect cells using recombinant baculoviruses. A mutation in the catalytic site of the P2 protease, C478A, (P2CA) completely abolished the processing of P12CA34, P12CA3 and P2CA3. Co-expression of P23 and P12CA34 in insect cells resulted in in trans cleavages at the P2/3 and P3/4 sites. Co-expression of P23 and P34 resulted in cleavage at the P3/4 site. In contrast, a construct with a mutation in the active site of the putative P4 protease, D6A, (P1234DA) was processed like the wild-type protein. P34 or its truncated forms were not processed when expressed alone. In insect cells, P4 was rapidly destroyed unless an inhibitor of proteosomal degradation was used. It is concluded that P2 is the only protease needed for the processing of SFV polyprotein P1234. Analysis of the cleavage products revealed that P23 or P2 could not cleave the P1/2 site in trans.


2009 ◽  
Vol 01 (01) ◽  
pp. 036-042 ◽  
Author(s):  
Tao Duan ◽  
Monique Ferguson ◽  
Lintian Yuan ◽  
Fangling Xu ◽  
Guangyu Li

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