scholarly journals Functional Requirements of the Yellow Fever Virus Capsid Protein

2007 ◽  
Vol 81 (12) ◽  
pp. 6471-6481 ◽  
Author(s):  
Chinmay G. Patkar ◽  
Christopher T. Jones ◽  
Yu-hsuan Chang ◽  
Ranjit Warrier ◽  
Richard J. Kuhn
Keyword(s):  
Capsid Protein ◽  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Virus Assembly ◽  
Fever Virus ◽  
Site Directed Mutagenesis ◽  
Packaging System ◽  
Virus Capsid ◽  
Double Mutation ◽  
Virus Capsid Protein

ABSTRACT Although it is known that the flavivirus capsid protein is essential for genome packaging and formation of infectious particles, the minimal requirements of the dimeric capsid protein for virus assembly/disassembly have not been characterized. By use of a trans-packaging system that involved packaging a yellow fever virus (YFV) replicon into pseudo-infectious particles by supplying the YFV structural proteins using a Sindbis virus helper construct, the functional elements within the YFV capsid protein (YFC) were characterized. Various N- and C-terminal truncations, internal deletions, and point mutations of YFC were analyzed for their ability to package the YFV replicon. Consistent with previous reports on the tick-borne encephalitis virus capsid protein, YFC demonstrates remarkable functional flexibility. Nearly 40 residues of YFC could be removed from the N terminus while the ability to package replicon RNA was retained. Additionally, YFC containing a deletion of approximately 27 residues of the C terminus, including a complete deletion of C-terminal helix 4, was functional. Internal deletions encompassing the internal hydrophobic sequence in YFC were, in general, tolerated to a lesser extent. Site-directed mutagenesis of helix 4 residues predicted to be involved in intermonomeric interactions were also analyzed, and although single mutations did not affect packaging, a YFC with the double mutation of leucine 81 and valine 88 was nonfunctional. The effects of mutations in YFC on the viability of YFV infection were also analyzed, and these results were similar to those obtained using the replicon packaging system, thus underscoring the flexibility of YFC with respect to the requirements for its functioning.

scholarly journals Functional Requirements of the Yellow Fever Virus Capsid Protein

2007 ◽  
Vol 81 (24) ◽  
pp. 13944-13944 ◽  
Author(s):  
Chinmay G. Patkar ◽  
Christopher T. Jones ◽  
Yu-hsuan Chang ◽  
Ranjit Warrier ◽  
Richard J. Kuhn
Keyword(s):  
Capsid Protein ◽  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Functional Requirements ◽  
Virus Capsid ◽  
Virus Capsid Protein

scholarly journals Yellow fever virus capsid protein is a potent suppressor of RNA silencing that binds double-stranded RNA

2016 ◽  
Vol 113 (48) ◽  
pp. 13863-13868 ◽  
Author(s):  
Glady Hazitha Samuel ◽  
Michael R. Wiley ◽  
Atif Badawi ◽  
Zach N. Adelman ◽  
Kevin M. Myles
Keyword(s):  
Yellow Fever ◽  
Rna Silencing ◽  
Yellow Fever Virus ◽  
Fever Virus ◽  
Diverse Range ◽  
Vector Mosquito ◽  
Invertebrate Animals ◽  
Rna Pathways ◽  
Suppressor Of Rna Silencing ◽  
Virus Capsid Protein

Mosquito-borne flaviviruses, including yellow fever virus (YFV), Zika virus (ZIKV), and West Nile virus (WNV), profoundly affect human health. The successful transmission of these viruses to a human host depends on the pathogen’s ability to overcome a potentially sterilizing immune response in the vector mosquito. Similar to other invertebrate animals and plants, the mosquito’s RNA silencing pathway comprises its primary antiviral defense. Although a diverse range of plant and insect viruses has been found to encode suppressors of RNA silencing, the mechanisms by which flaviviruses antagonize antiviral small RNA pathways in disease vectors are unknown. Here we describe a viral suppressor of RNA silencing (VSR) encoded by the prototype flavivirus, YFV. We show that the YFV capsid (YFC) protein inhibits RNA silencing in the mosquitoAedes aegyptiby interfering with Dicer. This VSR activity appears to be broadly conserved in the C proteins of other medically important flaviviruses, including that of ZIKV. These results suggest that a molecular “arms race” between vector and pathogen underlies the continued existence of flaviviruses in nature.

scholarly journals Rubella virus capsid protein structure and its role in virus assembly and infection

2013 ◽  
Vol 110 (50) ◽  
pp. 20105-20110 ◽  
Author(s):  
V. Mangala Prasad ◽  
S. D. Willows ◽  
A. Fokine ◽  
A. J. Battisti ◽  
S. Sun ◽  
...  
Keyword(s):  
Protein Structure ◽  
Capsid Protein ◽  
Rubella Virus ◽  
Virus Assembly ◽  
Virus Capsid ◽  
Virus Capsid Protein

scholarly journals Role of the Transmembrane Domains of prM and E Proteins in the Formation of Yellow Fever Virus Envelope

2003 ◽  
Vol 77 (2) ◽  
pp. 813-820 ◽  
Author(s):  
Anne Op De Beeck ◽  
Richard Molenkamp ◽  
Mélanie Caron ◽  
Amena Ben Younes ◽  
Peter Bredenbeek ◽  
...  
Keyword(s):  
Yellow Fever ◽  
Yellow Fever Virus ◽  
Virus Assembly ◽  
Transmembrane Domains ◽  
Fever Virus ◽  
Insertion Mutagenesis ◽  
E Proteins ◽  
Virus Envelope ◽  
Subviral Particle

ABSTRACT Flavivirus envelope proteins have been shown to play a major role in virus assembly. These proteins are anchored into cellular and viral membranes by their C-terminal domain. These domains are composed of two hydrophobic stretches separated by a short hydrophilic segment containing at least one charged residue. We investigated the role of the transmembrane domains of prM and E in the envelope formation of the flavivirus yellow fever virus (YFV). Alanine scanning insertion mutagenesis has been used to examine the role of the transmembrane domains of prM and E in YFV subviral particle formation. Most of the insertions had a dramatic effect on the release of YFV subviral particles. Some of these mutations were introduced into the viral genome. The ability of these mutant viruses to produce infectious particles was severely reduced. The alanine insertions did not affect prM-E heterodimerization. In addition, replacement of the charged residues present in the middle of the transmembrane domains had no effect on subviral particle release. Taken together, these data indicate that the transmembrane domains of prM and E play a crucial role in the biogenesis of YFV envelope. In addition, these data indicate some differences between the transmembrane domains of the hepaciviruses and the flaviviruses.

scholarly journals Fine Mapping of a cis-Acting Sequence Element in Yellow Fever Virus RNA That Is Required for RNA Replication and Cyclization

2003 ◽  
Vol 77 (3) ◽  
pp. 2265-2270 ◽  
Author(s):  
Jeroen Corver ◽  
Edith Lenches ◽  
Kayla Smith ◽  
R. Aaron Robison ◽  
Trisha Sando ◽  
...  
Keyword(s):  
Amino Acids ◽  
Capsid Protein ◽  
Yellow Fever ◽  
Fine Mapping ◽  
Yellow Fever Virus ◽  
Rna Replication ◽  
Fever Virus ◽  
Sequence Element ◽  
Complementary Sequence ◽  
Virus Rna

ABSTRACT We present fine mapping of a cis-acting nucleotide sequence found in the 5′ region of yellow fever virus genomic RNA that is required for RNA replication. There is evidence that this sequence interacts with a complementary sequence in the 3′ region of the genome to cyclize the RNA. Replicons were constructed that had various deletions in the 5′ region encoding the capsid protein and were tested for their ability to replicate. We found that a sequence of 18 nucleotides (residues 146 to 163 of the yellow fever virus genome, which encode amino acids 9 to 14 of the capsid protein) is essential for replication of the yellow fever virus replicon and that a slightly longer sequence of 21 nucleotides (residues 146 to 166, encoding amino acids 9 to 15) is required for full replication. This region is larger than the core sequence of 8 nucleotides conserved among all mosquito-borne flaviviruses and contains instead the entire sequence previously proposed to be involved in cyclization of yellow fever virus RNA.

scholarly journals Yellow Fever Virus NS3 Plays an Essential Role in Virus Assembly Independent of Its Known Enzymatic Functions

2008 ◽  
Vol 82 (7) ◽  
pp. 3342-3352 ◽  
Author(s):  
Chinmay G. Patkar ◽  
Richard J. Kuhn
Keyword(s):  
Yellow Fever ◽  
Infectious Virus ◽  
Yellow Fever Virus ◽  
Virus Assembly ◽  
Nonstructural Protein ◽  
Fever Virus ◽  
Helicase Domain ◽  
Genome Replication ◽  
Wild Type ◽  
Nonstructural Proteins

ABSTRACT In flaviviruses it has been proposed that there is a coupling between genome replication and virion assembly and that nonstructural proteins are involved in this process. It was previously reported that mutations in yellow fever virus (YFV) nonstructural protein NS2A blocked production of infectious virus and that this block could be released by a suppressor mutation in NS3. Here, based on studies using a YFV replicon-based trans-packaging system as well as full-length YFV cDNA, we report that mutation of a conserved tryptophan at position 349 in the helicase domain of NS3 blocks production of infectious virus particles, revealing an as-yet-unknown role for NS3 in virus assembly. Mutation of tryptophan 349 to alanine (W349A) had no effect on viral replication, as demonstrated by wild-type levels of viral RNA amplification and protein expression in W349A-transfected cells. Although release of infectious virus was not detected, release of capsidless subviral particles was not blocked. The assembly defect in W349A could be trans-complemented inefficiently using BHK-REP cells (a cell line containing persistently replicating YFV replicon RNA). trans-complementation was also demonstrated by supplying wild-type NS2B-3 or NS3 protein alone as well as by supplying inactive NS2B-3 protein, indicating that this function of NS3 in virus assembly was independent of its known enzymatic functions.

scholarly journals Analyses of Phosphorylation Events in the Rubella Virus Capsid Protein: Role in Early Replication Events

2006 ◽  
Vol 80 (14) ◽  
pp. 6917-6925 ◽  
Author(s):  
LokMan J. Law ◽  
Carolina S. Ilkow ◽  
Wen-Pin Tzeng ◽  
Matthew Rawluk ◽  
David T. Stuart ◽  
...  
Keyword(s):  
Capsid Protein ◽  
Rubella Virus ◽  
Rna Binding ◽  
Virus Assembly ◽  
Binding Activity ◽  
Amino Acid Residues ◽  
Direct Role ◽  
Virus Capsid ◽  
Early Replication ◽  
Virus Capsid Protein

ABSTRACT The Rubella virus capsid protein is phosphorylated prior to virus assembly. Our previous data are consistent with a model in which dynamic phosphorylation of the capsid regulates its RNA binding activity and, in turn, nucleocapsid assembly. In the present study, the process of capsid phosphorylation was examined in further detail. We show that phosphorylation of serine 46 in the RNA binding region of the capsid is required to trigger phosphorylation of additional amino acid residues that include threonine 47. This residue likely plays a direct role in regulating the binding of genomic RNA to the capsid. We also provide evidence which suggests that the capsid is dephosphorylated prior to or during virus budding. Finally, whereas the phosphorylation state of the capsid does not directly influence the rate of synthesis of viral RNA and proteins or the assembly and secretion of virions, the presence of phosphate on the capsid is critical for early events in virus replication, most likely the uncoating of virions and/or disassembly of nucleocapsids.

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