Formation and characterization of the trimeric form of the fusion protein of Semliki Forest virus

D. L. Gibbons, A. Ahn, P. K. Chatterjee, Margaret Kielian

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Enveloped animal viruses infect cells via fusion of the viral membrane with a host cell membrane. Fusion is mediated by a viral envelope glycoprotein, which for a number of enveloped animal viruses rearranges itself during fusion to form a trimeric α-helical coiled-coil structure. This conformational change from the metastable, nonfusogenic form of the spike protein to the highly stable form involved in fusion can be induced by physiological activators of virus fusion and also by a variety of destabilizing conditions. The E1 spike protein subunit of Semliki Forest virus (SFV) triggers membrane fusion upon exposure to mildly acidic pH and forms a homotrimer that appears necessary for fusion. We have here demonstrated that formation of the E1 homotrimer was efficiently triggered under low-pH conditions but not by perturbants such as heat or urea, despite their induction of generalized conformational changes in the E1 and E2 subunits and partial exposure of an acid-specific E1 epitope. We used a sensitive fluorescence assay to show that neither heat nor urea treatment triggered SFV-liposome fusion at neutral pH, although either treatment inactivated subsequent low-pH-triggered fusion activity. Once formed, the low-pH-induced E1 homotrimer was very stable and was only dissociated under harsh conditions such as heating in sodium dodecyl sulfate. Taken together, these data, as well as protein structure predictions, suggest a model in which the less stable native E1 subunit specifically responds to low pH to form the more stable E1 homotrimer via conformational changes different from those of the coiled-coil type of fusion proteins.

Original languageEnglish (US)
Pages (from-to)7772-7780
Number of pages9
JournalJournal of Virology
Volume74
Issue number17
DOIs
StatePublished - 2000

Fingerprint

Semliki Forest virus
Semliki forest virus
Proteins
proteins
Viruses
heat
Urea
urea
Hot Temperature
Virus Internalization
cell fusion
Cell Fusion
Protein Subunits
sodium dodecyl sulfate
protein subunits
protein structure
Liposomes
Sodium Dodecyl Sulfate
Heating
epitopes

ASJC Scopus subject areas

  • Immunology

Cite this

Formation and characterization of the trimeric form of the fusion protein of Semliki Forest virus. / Gibbons, D. L.; Ahn, A.; Chatterjee, P. K.; Kielian, Margaret.

In: Journal of Virology, Vol. 74, No. 17, 2000, p. 7772-7780.

Research output: Contribution to journalArticle

Gibbons, D. L. ; Ahn, A. ; Chatterjee, P. K. ; Kielian, Margaret. / Formation and characterization of the trimeric form of the fusion protein of Semliki Forest virus. In: Journal of Virology. 2000 ; Vol. 74, No. 17. pp. 7772-7780.
@article{cc7b268408644c4fbaaff932402a0889,
title = "Formation and characterization of the trimeric form of the fusion protein of Semliki Forest virus",
abstract = "Enveloped animal viruses infect cells via fusion of the viral membrane with a host cell membrane. Fusion is mediated by a viral envelope glycoprotein, which for a number of enveloped animal viruses rearranges itself during fusion to form a trimeric α-helical coiled-coil structure. This conformational change from the metastable, nonfusogenic form of the spike protein to the highly stable form involved in fusion can be induced by physiological activators of virus fusion and also by a variety of destabilizing conditions. The E1 spike protein subunit of Semliki Forest virus (SFV) triggers membrane fusion upon exposure to mildly acidic pH and forms a homotrimer that appears necessary for fusion. We have here demonstrated that formation of the E1 homotrimer was efficiently triggered under low-pH conditions but not by perturbants such as heat or urea, despite their induction of generalized conformational changes in the E1 and E2 subunits and partial exposure of an acid-specific E1 epitope. We used a sensitive fluorescence assay to show that neither heat nor urea treatment triggered SFV-liposome fusion at neutral pH, although either treatment inactivated subsequent low-pH-triggered fusion activity. Once formed, the low-pH-induced E1 homotrimer was very stable and was only dissociated under harsh conditions such as heating in sodium dodecyl sulfate. Taken together, these data, as well as protein structure predictions, suggest a model in which the less stable native E1 subunit specifically responds to low pH to form the more stable E1 homotrimer via conformational changes different from those of the coiled-coil type of fusion proteins.",
author = "Gibbons, {D. L.} and A. Ahn and Chatterjee, {P. K.} and Margaret Kielian",
year = "2000",
doi = "10.1128/JVI.74.17.7772-7780.2000",
language = "English (US)",
volume = "74",
pages = "7772--7780",
journal = "Journal of Virology",
issn = "0022-538X",
publisher = "American Society for Microbiology",
number = "17",

}

TY - JOUR

T1 - Formation and characterization of the trimeric form of the fusion protein of Semliki Forest virus

AU - Gibbons, D. L.

AU - Ahn, A.

AU - Chatterjee, P. K.

AU - Kielian, Margaret

PY - 2000

Y1 - 2000

N2 - Enveloped animal viruses infect cells via fusion of the viral membrane with a host cell membrane. Fusion is mediated by a viral envelope glycoprotein, which for a number of enveloped animal viruses rearranges itself during fusion to form a trimeric α-helical coiled-coil structure. This conformational change from the metastable, nonfusogenic form of the spike protein to the highly stable form involved in fusion can be induced by physiological activators of virus fusion and also by a variety of destabilizing conditions. The E1 spike protein subunit of Semliki Forest virus (SFV) triggers membrane fusion upon exposure to mildly acidic pH and forms a homotrimer that appears necessary for fusion. We have here demonstrated that formation of the E1 homotrimer was efficiently triggered under low-pH conditions but not by perturbants such as heat or urea, despite their induction of generalized conformational changes in the E1 and E2 subunits and partial exposure of an acid-specific E1 epitope. We used a sensitive fluorescence assay to show that neither heat nor urea treatment triggered SFV-liposome fusion at neutral pH, although either treatment inactivated subsequent low-pH-triggered fusion activity. Once formed, the low-pH-induced E1 homotrimer was very stable and was only dissociated under harsh conditions such as heating in sodium dodecyl sulfate. Taken together, these data, as well as protein structure predictions, suggest a model in which the less stable native E1 subunit specifically responds to low pH to form the more stable E1 homotrimer via conformational changes different from those of the coiled-coil type of fusion proteins.

AB - Enveloped animal viruses infect cells via fusion of the viral membrane with a host cell membrane. Fusion is mediated by a viral envelope glycoprotein, which for a number of enveloped animal viruses rearranges itself during fusion to form a trimeric α-helical coiled-coil structure. This conformational change from the metastable, nonfusogenic form of the spike protein to the highly stable form involved in fusion can be induced by physiological activators of virus fusion and also by a variety of destabilizing conditions. The E1 spike protein subunit of Semliki Forest virus (SFV) triggers membrane fusion upon exposure to mildly acidic pH and forms a homotrimer that appears necessary for fusion. We have here demonstrated that formation of the E1 homotrimer was efficiently triggered under low-pH conditions but not by perturbants such as heat or urea, despite their induction of generalized conformational changes in the E1 and E2 subunits and partial exposure of an acid-specific E1 epitope. We used a sensitive fluorescence assay to show that neither heat nor urea treatment triggered SFV-liposome fusion at neutral pH, although either treatment inactivated subsequent low-pH-triggered fusion activity. Once formed, the low-pH-induced E1 homotrimer was very stable and was only dissociated under harsh conditions such as heating in sodium dodecyl sulfate. Taken together, these data, as well as protein structure predictions, suggest a model in which the less stable native E1 subunit specifically responds to low pH to form the more stable E1 homotrimer via conformational changes different from those of the coiled-coil type of fusion proteins.

UR - http://www.scopus.com/inward/record.url?scp=0033881011&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033881011&partnerID=8YFLogxK

U2 - 10.1128/JVI.74.17.7772-7780.2000

DO - 10.1128/JVI.74.17.7772-7780.2000

M3 - Article

C2 - 10933683

AN - SCOPUS:0033881011

VL - 74

SP - 7772

EP - 7780

JO - Journal of Virology

JF - Journal of Virology

SN - 0022-538X

IS - 17

ER -