The NS1 protein of tick-borne encephalitis virus forms multimeric species upon secretion from the host cell

Crooks, Alan J.; Lee, John M.; Easterbrook, Linda; Тимофеев, А В; Stephenson, John

doi:10.1099/0022-1317-75-12-3453

Cited by 74 publications

(82 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The very narrow interfaces observed between the dimeric subunits, together with the previously reported instability of the NS1 hexamer in nonionic detergents (20,33) and its resistance to high molarities of salt or to chelating agents ( Fig. S3), indicated that the dimers are essentially held together by weak hydrophobic interactions.…”

Section: Denv Ns1 Dimeric Subunits Behave As Membranous Proteins Inmentioning

confidence: 75%

Secreted dengue virus nonstructural protein NS1 is an atypical barrel-shaped high-density lipoprotein

Gutsche

Coulibaly

Voss

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

264

294

View full text Add to dashboard Cite

Dengue virus (DENV) causes the major arboviral disease of the tropics, characterized in its severe forms by signs of hemorrhage and plasma leakage. DENV encodes a nonstructural glycoprotein, NS1, that associates with intracellular membranes and the cell surface. NS1 is eventually secreted as a soluble hexamer from DENV-infected cells and circulates in the bloodstream of infected patients. Extracellular NS1 has been shown to modulate the complement system and to enhance DENV infection, yet its structure and function remain essentially unknown. By combining cryoelectron microscopy analysis with a characterization of NS1 amphipathic properties, we show that the secreted NS1 hexamer forms a lipoprotein particle with an open-barrel protein shell and a prominent central channel rich in lipids. Biochemical and NMR analyses of the NS1 lipid cargo reveal the presence of triglycerides, bound at an equimolar ratio to the NS1 protomer, as well as cholesteryl esters and phospholipids, a composition evocative of the plasma lipoproteins involved in vascular homeostasis. This study suggests that DENV NS1, by mimicking or hijacking lipid metabolic pathways, contributes to endothelium dysfunction, a key feature of severe dengue disease.arbovirus | dengue hemorrhagic fever | amphiphilic proteins | secretion

show abstract

Section: Denv Ns1 Dimeric Subunits Behave As Membranous Proteins Inmentioning

confidence: 75%

Secreted dengue virus nonstructural protein NS1 is an atypical barrel-shaped high-density lipoprotein

Gutsche

Coulibaly

Voss

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

264

294

View full text Add to dashboard Cite

show abstract

“…Under conditions of SDS-PAGE, WNV NS1 migrated as a dimer, with an apparent molecular mass of ϳ80 kDa; boiling of samples prior to electrophoresis converted NS1 from a dimer to a monomer ( Fig. 1C), as has been observed for DEN, JEV, and TBE NS1 (10,23,25,53). Finally, insect cell-soluble WNV NS1 was glycosylated, as treatment with PNGase F reduced the apparent molecular weight of recombinant NS1 to ϳ40 kDa (Fig.…”

Section: Resultsmentioning

confidence: 96%

Antibodies against West Nile Virus Nonstructural Protein NS1 Prevent Lethal Infection through Fc γ Receptor-Dependent and -Independent Mechanisms

Chung

Nybakken

Thompson

et al. 2006

J Virol

226

239

View full text Add to dashboard Cite

The flavivirus nonstructural protein NS1 is a highly conserved secreted glycoprotein that does not package with the virion. Immunization with NS1 elicits a protective immune response against yellow fever, dengue, and tick-borne encephalitis flaviviruses through poorly defined mechanisms. In this study, we purified a recombinant, secreted form of West Nile virus (WNV) NS1 glycoprotein from baculovirus-infected insect cells and generated 22 new NS1-specific monoclonal antibodies (MAbs). By performing competitive binding assays and expressing truncated NS1 proteins on the surface of yeast (Saccharomyces cerevisiae) and in bacteria, we mapped 21 of the newly generated MAbs to three NS1 fragments. Prophylaxis of C57BL/6 mice with any of four MAbs (10NS1, 14NS1, 16NS1, and 17NS1) strongly protected against lethal WNV infection (75 to 95% survival, respectively) compared to saline-treated controls (17% survival). In contrast, other anti-NS1 MAbs of the same isotype provided no significant protection. Notably, 14NS1 and 16NS1 also demonstrated marked efficacy as postexposure therapy, even when administered as a single dose 4 days after infection. Virologic analysis showed that 17NS1 protects at an early stage in infection through a C1q-independent and Fc ␥ receptor-dependent pathway. Interestingly, 14NS1, which maps to a distinct region on NS1, protected through a C1q-and Fc ␥ receptor-independent mechanism. Overall, our data suggest that distinct regions of NS1 can elicit protective humoral immunity against WNV through different mechanisms.West Nile virus (WNV) is a single-stranded, positive-senseenveloped RNA virus that is maintained in nature through a mosquito-bird-mosquito transmission cycle. It is endemic in parts of Africa, Europe, the Middle East, and Asia, and outbreaks now occur annually in North America. Humans, which are dead-end hosts, can develop a febrile illness that progresses to a meningitis or encephalitis syndrome (32). At present, treatment is supportive, and no vaccine exists for human use.A member of the Flaviviridae family, WNV is closely related to other major human pathogens such as yellow fever (YF), dengue (DEN), tick-borne encephalitis (TBE), Japanese encephalitis (JEV), and Murray Valley encephalitis (MVE) viruses. The 10.7-kilobase genome is translated as a single polyprotein, which is then cleaved into three structural proteins (C, prM/M, and E) and seven nonstructural (NS) proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B, and NS5) by both virus-and host-encoded proteases (5). The NS proteins include an RNA-dependent RNA polymerase (NS5), a helicase/protease (NS3), and other proteins that form part of the viral replication complex (36, 37).NS1 is a highly conserved 48-kDa glycoprotein with 12 invariant cysteine residues. Although the disulfide linkage arrangement of MVE and DEN NS1 has been described (4, 66), structural analysis is currently lacking. NS1 is inserted into the lumen of the endoplasmic reticulum via a signal peptide that is cleaved cotranslationally by a cellular signalase to gene...

show abstract

“…After chase times between 30 min and 4 h, cell-associated and secreted TBE virus envelope proteins were immunoprecipitated and analyzed as described above. In addition to prM and E, the polyclonal antiserum used recognized the nonstructural protein NS1, which is expressed in infected cells and secreted as multimers independently of the virion (14).…”

Section: Intracellular Localization Of Tbe Virus Envelope Proteins Exmentioning

confidence: 99%

Intracellular Assembly and Secretion of Recombinant Subviral Particles from Tick-Borne Encephalitis Virus

Lorenz

Kartenbeck

Mezzacasa

et al. 2003

J Virol

109

View full text Add to dashboard Cite

It is believed that flavivirus assembly occurs by intracellular budding of the nucleocapsid into the lumen of the endoplasmic reticulum (ER). Recombinant expression of tick-borne encephalitis (TBE) virus envelope proteins prM and E in mammalian cells leads to their incorporation into enveloped recombinant subviral particles (RSPs), which have been used as a model system for studying assembly and entry processes and are also promising vaccine candidates. In this study, we analyzed the formation and secretion of TBE virus RSPs and of a membrane anchor-free E homodimer in mammalian cells. Immunofluorescence microscopy showed that E was accumulated in the lumen of the ER. RSPs were observed by electron microscopy in the rough and smooth ER and in downstream compartments of the secretory pathway. About 75% of the particles appeared to be of the size expected for RSPs (about 30 nm in diameter), but a number of larger particles and tubular structures were also observed in these compartments. Secretion of membrane anchor-free E dimers was detected 30 min after synthesis of prM and E, and secretion of RSPs was detected 1 h after synthesis of prM and E. We also found that the presence of the single N-linked oligosaccharide side chain on the E protein and its trimming by glucosidases was necessary for secretion of RSPs and truncated E dimers. Our results suggest that incorporation of prM and E into RSPs occurs at the ER membrane without other viral elements being required, followed by rapid transport along the compartments of the secretory pathway and secretion. Moreover, the carbohydrate side chain of E is involved in at least one assembly or transport step.

show abstract

The NS1 protein of tick-borne encephalitis virus forms multimeric species upon secretion from the host cell

Cited by 74 publications

References 28 publications

Secreted dengue virus nonstructural protein NS1 is an atypical barrel-shaped high-density lipoprotein

Secreted dengue virus nonstructural protein NS1 is an atypical barrel-shaped high-density lipoprotein

Antibodies against West Nile Virus Nonstructural Protein NS1 Prevent Lethal Infection through Fc γ Receptor-Dependent and -Independent Mechanisms

Intracellular Assembly and Secretion of Recombinant Subviral Particles from Tick-Borne Encephalitis Virus

Contact Info

Product

Resources

About