The alphavirus E2 membrane-proximal domain impacts capsid interaction and glycoprotein lattice formation

Emily A. Byrd, Margaret Kielian

Research output: Contribution to journalArticle

Abstract

Alphaviruses are small enveloped RNA viruses that bud from the host cell plasma membrane. Alphavirus particles have a highly organized structure, with a nucleocapsid core containing the RNA genome surrounded by the capsid protein, and a viral envelope containing 80 spikes, each a trimer of heterodimers of the E1 and E2 glycoproteins. The capsid protein and envelope proteins are both arranged in organized lattices that are linked via the interaction of the E2 cytoplasmic tail/ endodomain with the capsid protein. We previously characterized the role of two highly conserved histidine residues, H348 and H352, located in an external, juxtamembrane region of the E2 protein termed the D-loop. Alanine substitutions of H348 and H352 inhibit virus growth by impairing late steps in the assembly/budding of virus particles at the plasma membrane. To investigate this budding defect, we selected for revertants of the E2-H348/352A double mutant. We identified eleven second-site revertants with improved virus growth and mutations in the capsid, E2 and E1 proteins. Multiple isolates contained the mutation E2-T402K in the E2 endodomain or E1-T317I in the E1 ectodomain. Both of these mutations were shown to partially restore H348/352A growth and virus assembly/budding, while neither rescued the decreased thermostability of H348/352A. Within the alphavirus particle, these mutations are positioned to affect the E2-capsid interaction or the E1-mediated intertrimer interactions at the 5-fold axis of symmetry. Together, our results support a model in which the E2 D-loop promotes the formation of the glycoprotein lattice and its interactions with the internal capsid protein lattice.

Original languageEnglish (US)
Article numbere0188118
JournalJournal of Virology
Volume93
Issue number4
DOIs
StatePublished - Feb 1 2019

Fingerprint

Alphavirus
capsid
Capsid
Capsid Proteins
coat proteins
glycoproteins
Glycoproteins
mutation
Mutation
Membranes
Cell Membrane
plasma membrane
Growth
Viruses
Virus Release
Virus Assembly
Nucleocapsid
nucleocapsid
viruses
Proteins

Keywords

  • Alphavirus
  • Virus assembly
  • Virus budding

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Insect Science
  • Virology

Cite this

The alphavirus E2 membrane-proximal domain impacts capsid interaction and glycoprotein lattice formation. / Byrd, Emily A.; Kielian, Margaret.

In: Journal of Virology, Vol. 93, No. 4, e0188118, 01.02.2019.

Research output: Contribution to journalArticle

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