scholarly journals Membrane Association of African Horsesickness Virus Nonstructural Protein NS3 Determines Its Cytotoxicity

Virology ◽  
2001 ◽  
Vol 279 (2) ◽  
pp. 499-508 ◽  
Author(s):  
Michelle van Niekerk ◽  
Carel C. Smit ◽  
Wilma C. Fick ◽  
Vida van Staden ◽  
Henk Huismans
Keyword(s):  
Nonstructural Protein ◽  
Membrane Association ◽  
Nonstructural Protein Ns3 ◽  
African Horsesickness Virus

scholarly journals Variation of African horsesickness virus nonstructural protein NS3 in southern Africa

2001 ◽  
Vol 82 (1) ◽  
pp. 149-158 ◽  
Author(s):  
M. van Niekerk ◽  
V. van Staden ◽  
A. A. van Dijk ◽  
H. Huismans
Keyword(s):  
Southern Africa ◽  
Nonstructural Protein ◽  
Live Attenuated Vaccine ◽  
Field Isolates ◽  
Ns3 Protein ◽  
Current Vaccine ◽  
Outer Capsid ◽  
Reference Strains ◽  
Nonstructural Protein Ns3 ◽  
African Horsesickness Virus

NS3 protein sequences of recent African horsesickness virus (AHSV) field isolates, reference strains and current vaccine strains in southern Africa were determined and compared. The variation of AHSV NS3 was found to be as much as 36·3% across serotypes and 27·6% within serotypes. NS3 proteins of vaccine and field isolates of a specific serotype were found to differ between 2·3% and 9·7%. NS3 of field isolates within a serotype differed up to 11·1%. Our data indicate that AHSV NS3 is the second most variable AHSV protein, the most variable being the major outer capsid protein, VP2. The inferred phylogeny of AHSV NS3 corresponded well with the described NS3 phylogenetic clusters. The only exception was AHSV-8 NS3, which clustered into different groups than previously described. No obvious sequence markers could be correlated with virulence. Our results suggest that NS3 sequence variation data could be used to distinguish between field isolates and live attenuated vaccine strains of the same serotype.

scholarly journals Identification of a Novel Determinant for Membrane Association in Hepatitis C Virus Nonstructural Protein 4B

2009 ◽  
Vol 83 (12) ◽  
pp. 6257-6268 ◽  
Author(s):  
Jérôme Gouttenoire ◽  
Valérie Castet ◽  
Roland Montserret ◽  
Naveen Arora ◽  
Vincent Raussens ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Nonstructural Protein ◽  
Attenuated Total Reflection ◽  
Membrane Extraction ◽  
Phospholipid Bilayer ◽  
Membrane Association ◽  
Acceptor Site ◽  
Replication Complex ◽  
Α Helix

ABSTRACT Nonstructural protein 4B (NS4B) plays an essential role in the formation of the hepatitis C virus (HCV) replication complex. It is a relatively poorly characterized integral membrane protein predicted to comprise four transmembrane segments in its central portion. Here, we describe a novel determinant for membrane association represented by amino acids (aa) 40 to 69 in the N-terminal portion of NS4B. This segment was sufficient to target and tightly anchor the green fluorescent protein to cellular membranes, as assessed by fluorescence microscopy as well as membrane extraction and flotation analyses. Circular dichroism and nuclear magnetic resonance structural analyses showed that this segment comprises an amphipathic α-helix extending from aa 42 to 66. Attenuated total reflection infrared spectroscopy and glycosylation acceptor site tagging revealed that this amphipathic α-helix has the potential to traverse the phospholipid bilayer as a transmembrane segment, likely upon oligomerization. Alanine substitution of the fully conserved aromatic residues on the hydrophobic helix side abrogated membrane association of the segment comprising aa 40 to 69 and disrupted the formation of a functional replication complex. These results provide the first atomic resolution structure of an essential membrane-associated determinant of HCV NS4B.

Comparison of the nonstructural protein, NS3, of tick-borne and insect-borne orbiviruses

Virology ◽  
1992 ◽  
Vol 187 (2) ◽  
pp. 841-844 ◽  
Author(s):  
Stephen R. Moss ◽  
Linda D. Jones ◽  
Patricia A. Nuttall
Keyword(s):  
Nonstructural Protein ◽  
Nonstructural Protein Ns3

scholarly journals Conserved Determinants for Membrane Association of Nonstructural Protein 5A fromHepatitis C Virus and Related Viruses

2006 ◽  
Vol 81 (6) ◽  
pp. 2745-2757 ◽  
Author(s):  
Volker Brass ◽  
Zsuzsanna Pal ◽  
Nicolas Sapay ◽  
Gilbert Deléage ◽  
Hubert E. Blum ◽  
...  
Keyword(s):  
Amino Acid ◽  
Nonstructural Protein ◽  
Alpha Helix ◽  
Laser Scanning Microscopy ◽  
Membrane Association ◽  
Alpha Helices ◽  
Replication Complex ◽  
Diarrhea Virus ◽  
Amphipathic Alpha Helix ◽  
Nonstructural Protein 5A

ABSTRACT Nonstructural protein 5A (NS5A) is a membrane-associated essential component of the hepatitis C virus (HCV) replication complex. An N-terminal amphipathic alpha helix mediates in-plane membrane association of HCV NS5A and at the same time is likely involved in specific protein-protein interactions required for the assembly of a functional replication complex. The aim of this study was to identify the determinants for membrane association of NS5A from the related GB viruses and pestiviruses. Although primary amino acid sequences differed considerably, putative membrane anchor domains with amphipathic features were predicted in the N-terminal domains of NS5A proteins from these viruses. Confocal laser scanning microscopy, as well as membrane flotation analyses, demonstrated that NS5As from GB virus B (GBV-B), GBV-C, and bovine viral diarrhea virus, the prototype pestivirus, display membrane association characteristics very similar to those of HCV NS5A. The N-terminal 27 to 33 amino acid residues of these NS5A proteins were sufficient for membrane association. Circular dichroism analyses confirmed the capacity of these segments to fold into alpha helices upon association with lipid-like molecules. Despite structural conservation, only very limited exchanges with sequences from related viruses were tolerated in the context of functional HCV RNA replication, suggesting virus-specific interactions of these segments. In conclusion, membrane association of NS5A by an N-terminal amphipathic alpha helix is a feature shared by HCV and related members of the family Flaviviridae. This observation points to conserved roles of the N-terminal amphipathic alpha helices of NS5A in replication complex formation.

scholarly journals Zika virus alters centrosome organization to suppress the innate immune response

2020 ◽  
Author(s):  
Andrew Kodani ◽  
Kristeene A. Knopp ◽  
Elizabeth Di Lullo ◽  
Hanna Retallack ◽  
Arnold R. Kriegstein ◽  
...  
Keyword(s):  
Immune Response ◽  
Immune Responses ◽  
Innate Immune Response ◽  
Zika Virus ◽  
Nonstructural Protein ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Zikv Infection ◽  
Centrosomal Proteins ◽  
Nonstructural Protein Ns3

AbstractZika virus (ZIKV) is a flavivirus transmitted via mosquitoes and sex to cause congenital neurodevelopmental defects, including microcephaly. Inherited forms of microcephaly (MCPH) are associated with disrupted centrosome organization. Similarly, we found that ZIKV infection disrupted centrosome organization. ZIKV infection disrupted the organization of centrosomal proteins including CEP63, a MCPH-associated protein. The ZIKV nonstructural protein NS3 bound CEP63, and expression of NS3 was sufficient to alter centrosome architecture and CEP63 localization. Loss of CEP63 suppressed ZIKV-induced centrosome disorganization, indicating that ZIKV requires CEP63 to disrupt centrosome organization. ZIKV infection or loss of CEP63 decreased the centrosomal localization and stability of TANK-binding kinase 1 (TBK1), a regulator of the innate immune response. ZIKV infection or loss of CEP63 also increased the centrosomal accumulation of the CEP63 interactors, Mindbomb1 (MIB1) and DTX4, ubiquitin ligases that respectively activate and degrade TBK1. Therefore, we propose that ZIKV NS3 binds CEP63 to increase centrosomal DTX4 localization and destabilization of TBK1, thereby tempering the innate immune response. In addition to identifying a mechanism by which CEP63 controls the innate immune responses in ZIKV infection, we propose that the altered centrosomal organization caused by altered CEP63 function may contribute to ZIKV-associated microcephaly.

scholarly journals Novel Function of Bluetongue Virus NS3 Protein in Regulation of the MAPK/ERK Signaling Pathway

2019 ◽  
Vol 93 (16) ◽  
Author(s):  
Cindy Kundlacz ◽  
Marie Pourcelot ◽  
Aurore Fablet ◽  
Rayane Amaral Da Silva Moraes ◽  
Thibaut Léger ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Viral Replication ◽  
Translation Initiation ◽  
Bluetongue Virus ◽  
Nonstructural Protein ◽  
Blood Feeding ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Erk Pathway ◽  
Nonstructural Protein Ns3

ABSTRACTBluetongue virus (BTV) is an arbovirus transmitted by blood-feeding midges to a wide range of wild and domestic ruminants. In this report, we showed that BTV, through its nonstructural protein NS3 (BTV-NS3), is able to activate the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, as assessed by phosphorylation levels of ERK1/2 and the translation initiation factor eukaryotic translation initiation factor 4E (eIF4E). By combining immunoprecipitation of BTV-NS3 and mass spectrometry analysis from both BTV-infected and NS3-transfected cells, we identified the serine/threonine-protein kinase B-Raf (BRAF), a crucial player in the MAPK/ERK pathway, as a new cellular interactor of BTV-NS3. BRAF silencing led to a significant decrease in the MAPK/ERK activation by BTV, supporting a model wherein BTV-NS3 interacts with BRAF to activate this signaling cascade. This positive regulation acts independently of the role of BTV-NS3 in counteracting the induction of the alpha/beta interferon response. Furthermore, the intrinsic ability of BTV-NS3 to bind BRAF and activate the MAPK/ERK pathway is conserved throughout multiple serotypes/strains but appears to be specific to BTV compared to other members ofOrbivirusgenus. Inhibition of MAPK/ERK pathway with U0126 reduced viral titers, suggesting that BTV manipulates this pathway for its own replication. Altogether, our data provide molecular mechanisms that unravel a new essential function of NS3 during BTV infection.IMPORTANCEBluetongue virus (BTV) is responsible of the arthropod-borne disease bluetongue (BT) transmitted to ruminants by blood-feeding midges. In this report, we found that BTV, through its nonstructural protein NS3 (BTV-NS3), interacts with BRAF, a key component of the MAPK/ERK pathway. In response to growth factors, this pathway promotes cell survival and increases protein translation. We showed that BTV-NS3 enhances the MAPK/ERK pathway, and this activation is BRAF dependent. Treatment of MAPK/ERK pathway with the pharmacologic inhibitor U0126 impairs viral replication, suggesting that BTV manipulates this pathway for its own benefit. Our results illustrate, at the molecular level, how a single virulence factor has evolved to target a cellular function to increase its viral replication.

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