Both nonstructural proteins NS2B and NS3 are required for the proteolytic processing of dengue virus nonstructural proteins.
TLDR
This work constructed recombinant vaccinia viruses expressing various portions of the NS region of the dengue virus type 4 polyprotein and showed that NS2B was needed, apparently in cis, for NS3/NS4A cleavage and for a series of internal cleavages in NS3.Abstract:
The cleavages at the junctions of the flavivirus nonstructural (NS) proteins NS2A/NS2B, NS2B/NS3, NS3/NS4A, and NS4B/NS5 share an amino acid sequence motif and are presumably catalyzed by a virus-encoded protease. We constructed recombinant vaccinia viruses expressing various portions of the NS region of the dengue virus type 4 polyprotein. By analyzing immune precipitates of 35S-labeled lysates of recombinant virus-infected cells, we could monitor the NS2A/NS2B, NS2B/NS3, and NS3/NS4A cleavages. A polyprotein composed of NS2A, NS2B, and the N-terminal 184 amino acids of NS3 was cleaved at the NS2A/NS2B and NS2B/NS3 junctions, whereas a similar polyprotein containing only the first 77 amino acids of NS3 was not cleaved. This finding is consistent with the proposal that the N-terminal 180 amino acids of NS3 constitute a protease domain. Polyproteins containing NS2A and NS3 with large in-frame deletions of NS2B were not cleaved at the NS2A/NS2B or NS2B/NS3 junctions. Coinfection with a recombinant expressing NS2B complemented these NS2B deletions for NS2B/NS3 cleavage and probably also for NS2A/NS2B cleavage. Thus, NS2B is also required for the NS2A/NS2B and NS2B/NS3 cleavages and can act in trans. Other experiments showed that NS2B was needed, apparently in cis, for NS3/NS4A cleavage and for a series of internal cleavages in NS3. Indirect evidence that NS3 can also act in trans was obtained. Models are discussed for a two-component protease activity requiring both NS2B and NS3.read more
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Flaviviridae :T he Viruses and Their Replication
TL;DR: The present research attacked the Flavivirus infection through two mechanisms: Membrane Reorganization and the Compartmentalization and Assembly and Release of Particles from Flaviv virus-infected Cells and Host Resistance to Flaviviral Infection.
Book ChapterDOI
Molecular biology of flaviviruses.
TL;DR: An overview of the molecular biology of the flaviviruses is presented, which are enveloped positive-strand RNA viruses capable of causing a number of important human diseases.
Journal ArticleDOI
Characterization of the hepatitis C virus-encoded serine proteinase: determination of proteinase-dependent polyprotein cleavage sites.
TL;DR: Deletion analyses suggest that the structural and NS2 regions of the polyprotein are not required for the HCV NS3 proteinase activity, and sequence comparison of the residues flanking these cleavage sites for all sequenced HCV strains reveals conserved residues which may play a role in determining HCV proteinase substrate specificity.
Journal ArticleDOI
Nonstructural protein 3 of the hepatitis C virus encodes a serine-type proteinase required for cleavage at the NS3/4 and NS4/5 junctions.
TL;DR: It is demonstrated that NS3 encodes the viral proteinase essential for generating the amino termini of NS4 and NS5.
Journal ArticleDOI
NS3 is a serine protease required for processing of hepatitis C virus polyprotein.
TL;DR: It is shown that the amino-terminal region of the HCV polyprotein is processed in vitro by cellular proteases releasing three structural proteins: p21 (core), gp37 (E1), and gp61 (E2), and implicate NS3 as a serine protease and demonstrate that a catalytically active NS3 is necessary for cleavage of the nonstructural region of HCV.
References
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TL;DR: The sequence of the entire RNA genome of the type flavivirus, yellow fever virus, has been obtained and implies that mature viral proteins are produced by posttranslational cleavage of a polyprotein precursor and has implications for flaviv virus RNA replication and for the evolutionary relation of this virus family to other RNA viruses.
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Evidence that the N-terminal domain of nonstructural protein NS3 from yellow fever virus is a serine protease responsible for site-specific cleavages in the viral polyprotein.
T J Chambers,R C Weir,Arash Grakoui,David W. McCourt,J F Bazan,Robert J. Fletterick,Charles M. Rice +6 more
TL;DR: To examine the putative proteolytic activity of NS3, segments of the yellow fever virus genome were subcloned into plasmid transcription/translation vectors and cell-free translation products were characterized and results suggest that a protease activity encoded within NS2B and the N-terminal one-third ofyellow fever virus NS3 is capable of cis-acting site-specific proteolysis at the NS2 B-NS3 cleavage site and dilution-insensitive cleavage
Journal ArticleDOI
Complete Nucleotide Sequence of the Japanese Encephalitis Virus Genome RNA
Hideo Sumiyoshi,Chisato Mori,Isao Fuke,Kouichi Morita,Satoshi Kuhara,Jun Kondou,Yo Kikuchi,Hiroshi Nagamatu,Akira Igarashi +8 more
TL;DR: The complete nucleotide sequence of the Japanese encephalitis virus (JEV) genome RNA was determined and it was found that the C-terminal region of the ORF may encode a RNA-dependent RNA polymerase which has significant sequence homology with those of other RNA viruses.