RESUMEN
Flavivirus remodels the host endoplasmic reticulum (ER) to generate replication compartments (RCs) as the fundamental structures to accommodate viral replication. Here, a centralized replication mode of flavivirus is reported, i.e., flavivirus concentrates host ER in perinuclear main replication compartments (MRCs) for efficient replication. Superresolution live-cell imaging demonstrated that flavivirus MRCs formed via a series of events, including multisite ER clustering, growth and merging of ER clusters, directional movement, and convergence in the perinuclear region. The dynamic activities of viral RCs are driven by nonstructural (NS) proteins and are independent of microtubules and actin. Moreover, disrupting MRCs formation by small molecule compounds inhibited flavivirus replication. Overall, the findings reveal unprecedented insight into dynamic ER reorganization by flavivirus and identify a new inhibition strategy.
Asunto(s)
Flavivirus , Flavivirus/metabolismo , Retículo Endoplásmico/metabolismo , Replicación ViralRESUMEN
Ros/MucR is a widespread family of bacterial zinc-finger-containing proteins that integrate multiple functions, such as symbiosis, virulence, transcription regulation, motility, production of surface components, and various other physiological processes in cells. This regulatory protein family is conserved in bacteria and is characterized by its zinc-finger motif, which has been proposed as the ancestral domain from which the eukaryotic C2H2 zinc-finger structure has evolved. The first prokaryotic zinc-finger domain found in the transcription regulator Ros was identified in Agrobacterium tumefaciens. In the past decades, a large body of evidence revealed Ros/MucR as pleiotropic transcriptional regulators that mainly act as repressors through oligomerization and binding to AT-rich target promoters. The N-terminal domain and the zinc-finger-bearing C-terminal region of these regulatory proteins are engaged in oligomerization and DNA binding, respectively. These properties of the Ros/MucR proteins are similar to those of xenogeneic silencers, such as H-NS, MvaT, and Lsr2, which are mainly found in other lineages. In fact, a novel functional model recently proposed for this protein family suggests that they act as H-NS-'like' gene silencers. The prokaryotic zinc-finger domain exhibits interesting structural and functional features that are different from that of its eukaryotic counterpart (a ßßßα topology), as it folds in a significantly larger zinc-binding globular domain (a ßßßαα topology). Phylogenetic analysis of Ros/MucR homologs suggests an ancestral origin of this type of protein in α-Proteobacteria. Furthermore, multiple duplications and lateral gene transfer events contributing to the diversity and phyletic distribution of these regulatory proteins were found in bacterial genomes.
Asunto(s)
Proteínas Bacterianas , Dedos de Zinc , Filogenia , Secuencia de Aminoácidos , Proteínas Bacterianas/metabolismo , Dedos de Zinc/genética , Factores de Transcripción/genética , Bacterias/metabolismo , Zinc/metabolismoRESUMEN
BACKGROUND: Hepatitis C virus (HCV) is an enveloped and positive-stranded RNA virus that is a major causative agent of chronic liver diseases worldwide. HCV has become the main cause of liver transplantations and there is no effective drug for all hepatitis genotypes. Elucidation of the life cycle and non-structural proteins of HCV, involved in viral replication, are attractive targets for the development of antiviral drugs.. METHODS: In this work, pharmacoinformatics approaches coupled with docking analyses were applied on HCV non-structural proteins to identify the novel potential hits and HCV drugs. Molecular docking analyses were carried out on HCV-approved drugs, followed by the ligandbased pharmacophore generation to screen the antiviral libraries for novel potential hits. RESULTS: Virtual screening technique has top-ranked five novel compounds (ZINC00607900, ZINC03635748, ZINC03875543, ZINC04097464, and ZINC12503102) along with their least binding energies (-8.0 kcal/mol, -6.1 kcal/mol, -7.5 kcal/mol, -7.4 kcal/mol, and -7.3 kcal/mol, respectively) and stability with the non-structural proteins target. CONCLUSION: These promising hits exhibited better absorption and ADMET properties as compared to the selected drug molecules. These potential compounds extracted from in silico approach may be significant in drug design and development against Hepatitis and other liver diseases.
Asunto(s)
Hepacivirus , Hepatitis C , Animales , Antivirales/química , Hepatitis C/tratamiento farmacológico , Ligandos , Simulación del Acoplamiento Molecular , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/metabolismoRESUMEN
Respiratory Syncytial Virus (RSV) is a highly prevalent virus that affects the majority of the population. The virus can cause severe disease in vulnerable populations leading to high hospitalization rates from bronchiolitis or secondary bacterial infections leading to pneumonia. Two early and non-structural proteins (Ns1 and Ns2), strongly over-ride the antiviral innate system but also diminish the adaptive response as well. This review will cover interactions of Ns1 and Ns2 with the host antiviral response with a focus on alterations to signaling pathways, cytokine gene expression, and effects of the Ns proteins on mitochondria.
Asunto(s)
Infecciones por Virus Sincitial Respiratorio , Virus Sincitial Respiratorio Humano , Proteínas no Estructurales Virales , Citocinas , Expresión Génica , Humanos , Virus Sincitial Respiratorio Humano/genética , Transducción de Señal , Proteínas no Estructurales Virales/genéticaRESUMEN
Despite the ever-increasing global incidence of dengue fever, there are no specific chemotherapy regimens for its treatment. Structural studies on dengue virus (DENV) proteins have revealed potential drug targets. Major DENV proteins such as the envelope protein and non-structural (NS) proteins 3 and 5 have been extensively investigated in antiviral studies, but with limited success in vitro. However, the minor NS proteins NS2 and NS4 have remained relatively underreported. Emerging evidence indicating their indispensable roles in virus propagation and host immunomodulation should encourage us to target these proteins for drug discovery. This review covers current knowledge on DENV NS2 and NS4 proteins from structural and functional perspectives and assesses their potential as targets for antiviral design. Antiviral targets in NS2A include surface-exposed transmembrane regions involved in pathogenesis, while those in NS2B include protease-binding sites in a conserved hydrophilic domain. Ideal drug targets in NS4A include helix α4 and the PEPEKQR sequence, which are essential for NS4A-2K cleavage and NS4A-NS4B association, respectively. In NS4B, the cytoplasmic loop connecting helices α5 and α7 is an attractive target for antiviral design owing to its role in dimerization and NS4B-NS3 interaction. Findings implicating NS2A, NS2B, and NS4A in membrane-modulation and viroporin-like activities indicate an opportunity to target these proteins by disrupting their association with membrane lipids. Despite the lack of 3D structural data, recent topological findings and progress in structure-prediction methods should be sufficient impetus for targeting NS2 and NS4 for drug design.
Asunto(s)
Virus del Dengue/metabolismo , Dengue/metabolismo , Proteínas no Estructurales Virales/metabolismo , Secuencia de Aminoácidos , Animales , Dengue/genética , Virus del Dengue/química , Virus del Dengue/genética , Humanos , Estructura Secundaria de Proteína , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/genéticaRESUMEN
Zika virus (ZIKV) encodes a precursor protein (also called polyprotein) of about 3424 amino acids that is processed by proteases to generate 10 mature proteins and a small peptide. In the present study, we characterized the chemical features, suborganelle distribution and potential function of each protein using Flag-tagged protein expression system. Western blot analysis revealed the molecular weight of the proteins and the polymerization of E, NS1, and NS3 proteins. In addition, we performed multi-labeled fluorescent immunocytochemistry and subcellular fractionation to determine the subcellular localization of these proteins in host cells. We found that 1) the capsid protein colocalizes with 3 different cellular organelles: nucleoli, Golgi apparatus, and lipid droplet; NS2b and NS4a are associated with the Golgi apparatus; 2) the capsid and NS1proteins distribute in both cytoplasm and nucleus, NS5 is a nuclear protein; 3) NS3 protein colocalizes with tubulin and affects Lamin A; 4) Envelope, PrM, and NS2a proteins co-localize with the endoplasmic reticulum; 5) NS1 is associated with autophagosomes and NS4b is related to early endosome; 6) NS5 forms punctate structures in the nucleus that associate with splicing compartments shown by SC35, leading to reduction of SC35 protein level and trafficking of SC35 from the nucleus to the cytoplasm. These data suggest that ZIKV generates 10 functional viral proteins that exhibit distinctive subcellular distribution in host cells.