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Topology of the membrane-associated hepatitis C virus protein NS4B

Lundin, Marika; Monne, Magnus; Widell, Anders LU ; von Heijne, Gunnar and Persson, Mats A. A. (2003) In Journal of Virology 77(9). p.5428-5438
Abstract
Hepatitis C virus (HCV) belongs to the Hepacivirus genus in the Flaviviridae family. Among the least known viral proteins in this family is the nonstructural protein NS4B, which has been suggested to be a part of the replication complex. Hydrophobicity plots indicate a common profile among the NS4B proteins from different members of the Flaviviridae family, suggesting a common function. In order to gain a deeper understanding of the nature of HCV NS4B, we have determined localization and topology of this protein by using recombinant HCV NS4B constructs. The protein localized to the endoplasmic reticulum (ER), but also induced a pattern of cytoplasmic foci positive for markers of the ER. Computer predictions of the membrane topology of NS4B... (More)
Hepatitis C virus (HCV) belongs to the Hepacivirus genus in the Flaviviridae family. Among the least known viral proteins in this family is the nonstructural protein NS4B, which has been suggested to be a part of the replication complex. Hydrophobicity plots indicate a common profile among the NS4B proteins from different members of the Flaviviridae family, suggesting a common function. In order to gain a deeper understanding of the nature of HCV NS4B, we have determined localization and topology of this protein by using recombinant HCV NS4B constructs. The protein localized to the endoplasmic reticulum (ER), but also induced a pattern of cytoplasmic foci positive for markers of the ER. Computer predictions of the membrane topology of NS4B suggested that it has four transmembrane segments. The N and C termini were anticipated to be localized in the cytoplasm, because they are processed by the cytoplasmic NS3 protein. By introducing glycosylation sites at various positions in HCV NS4B, we show that the C terminus is cytoplasmic and the loop around residue 161 is lumenal as predicted. Surprisingly, the N-terminal tail was translocated into the lumen in a considerable fraction of the NS4B molecules, most likely by a posttranslational process. Interestingly, NS4B proteins of the yellow fever and dengue viruses also have their N termini located in the ER lumen due to an N-terminal signal peptide not found in NS4B of HCV. A shared topology achieved in two different ways supports the notion of a common function for NS4B in Flaviviridae. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Journal of Virology
volume
77
issue
9
pages
5428 - 5438
publisher
American Society for Microbiology
external identifiers
  • pmid:12692244
  • wos:000182297200040
  • scopus:0344373790
ISSN
1098-5514
DOI
10.1128/JVI.77.9.5428-5438.2003
language
English
LU publication?
yes
id
065df865-753a-4917-a8a5-fa55dee36c5c (old id 141917)
alternative location
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12692244&query_hl=35
date added to LUP
2007-07-25 16:17:24
date last changed
2018-05-29 09:21:26
@article{065df865-753a-4917-a8a5-fa55dee36c5c,
  abstract     = {Hepatitis C virus (HCV) belongs to the Hepacivirus genus in the Flaviviridae family. Among the least known viral proteins in this family is the nonstructural protein NS4B, which has been suggested to be a part of the replication complex. Hydrophobicity plots indicate a common profile among the NS4B proteins from different members of the Flaviviridae family, suggesting a common function. In order to gain a deeper understanding of the nature of HCV NS4B, we have determined localization and topology of this protein by using recombinant HCV NS4B constructs. The protein localized to the endoplasmic reticulum (ER), but also induced a pattern of cytoplasmic foci positive for markers of the ER. Computer predictions of the membrane topology of NS4B suggested that it has four transmembrane segments. The N and C termini were anticipated to be localized in the cytoplasm, because they are processed by the cytoplasmic NS3 protein. By introducing glycosylation sites at various positions in HCV NS4B, we show that the C terminus is cytoplasmic and the loop around residue 161 is lumenal as predicted. Surprisingly, the N-terminal tail was translocated into the lumen in a considerable fraction of the NS4B molecules, most likely by a posttranslational process. Interestingly, NS4B proteins of the yellow fever and dengue viruses also have their N termini located in the ER lumen due to an N-terminal signal peptide not found in NS4B of HCV. A shared topology achieved in two different ways supports the notion of a common function for NS4B in Flaviviridae.},
  author       = {Lundin, Marika and Monne, Magnus and Widell, Anders and von Heijne, Gunnar and Persson, Mats A. A.},
  issn         = {1098-5514},
  language     = {eng},
  number       = {9},
  pages        = {5428--5438},
  publisher    = {American Society for Microbiology},
  series       = {Journal of Virology},
  title        = {Topology of the membrane-associated hepatitis C virus protein NS4B},
  url          = {http://dx.doi.org/10.1128/JVI.77.9.5428-5438.2003},
  volume       = {77},
  year         = {2003},
}