Pseudorevertants of a semliki forest virus fusion-blocking mutation reveal a critical interchain interaction in the core trimer

Catherine Y. Liu, Christen Besanceney, Yifan Song, Margaret Kielian

Research output: Contribution to journalArticle

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Abstract

Semliki Forest virus (SFV) is an enveloped alphavirus that infects cells by a low-pH-triggered membrane fusion reaction mediated by the viral E1 protein. E1 inserts into target membranes and refolds to a hairpin-like homotrimer containing a central core trimer and an outer layer composed of domain III and the juxtamembrane stem region. The key residues involved in mediating E1 trimerization are not well understood. We recently showed that aspartate 188 in the interface of the core trimer plays a critical role. Substitution with lysine (D188K) blocks formation of the core trimer and E1 trimerization and strongly inhibits virus fusion and infection. Here, we have isolated and characterized revertants that rescued the fusion and growth defects of D188K. These revertants included pseudorevertants containing acidic or polar neutral residues at E1 position 188 and a second-site revertant containing an E1 K176T mutation. Computational analysis using multiconformation continuum electrostatics revealed an important interaction bridging D188 of one chain with K176 of the adjacent chain in the core trimer. E1 K176 is completely conserved among the alphaviruses, and mutations of K176 to threonine (K176T) or isoleucine (K176I) produced similar fusion phenotypes as D188 mutants. Together, our data support a model in which a ring of three salt bridges formed by D188 and K176 stabilize the core trimer, a key intermediate of the alphavirus fusion protein.

Original languageEnglish (US)
Pages (from-to)11624-11633
Number of pages10
JournalJournal of Virology
Volume84
Issue number22
DOIs
StatePublished - Nov 2010

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Semliki Forest virus
Semliki forest virus
Alphavirus
mutation
threonine
Mutation
Threonine
aspartic acid
isoleucine
lysine
proteins
Membrane Fusion
Isoleucine
salts
phenotype
Viral Proteins
Virus Diseases
viruses
mutants
Static Electricity

ASJC Scopus subject areas

  • Immunology
  • Virology

Cite this

Pseudorevertants of a semliki forest virus fusion-blocking mutation reveal a critical interchain interaction in the core trimer. / Liu, Catherine Y.; Besanceney, Christen; Song, Yifan; Kielian, Margaret.

In: Journal of Virology, Vol. 84, No. 22, 11.2010, p. 11624-11633.

Research output: Contribution to journalArticle

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