An N-terminal domain helical motif of Prototype Foamy Virus Gag with dual functions essential for particle egress and viral infectivity

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Juliane Reh - , Institute of Medical Microbiology and Virology (Author)
  • Annett Stange - , Institute of Medical Microbiology and Virology (Author)
  • Anne Götz - , Institute of Medical Microbiology and Virology (Author)
  • Marlene Rönitz - , Institute of Medical Microbiology and Virology (Author)
  • Arend Große - , Institute of Medical Microbiology and Virology (Author)
  • Dirk Lindemann - , Institute of Medical Microbiology and Virology (Author)

Abstract

BACKGROUND: Foamy viruses (FVs) have developed a unique budding strategy within the retrovirus family. FV release requires co-expression and a highly specific interaction between capsid (Gag) and glycoprotein (Env), which cannot be complemented by heterologous Env proteins. The interaction domain in FV Env has been mapped in greater detail and resides mainly in the N-terminal tip of the cytoplasmic domain of the Env leader peptide subunit. In contrast, the corresponding domain within Gag is less well defined. Previous investigations suggest that it is located within the N-terminal part of the protein.

RESULTS: Here we characterized additional Gag interaction determinants of the prototype FV (PFV) isolate using a combination of particle release, GST pull-down and single cycle infectivity analysis assays. Our results demonstrate that a minimal PFV Gag protein comprising the N-terminal 129 aa was released into the supernatant, whereas proteins lacking this domain failed to do so. Fine mapping of domains within the N-terminus of PFV Gag revealed that the N-terminal 10 aa of PFV Gag were dispensable for viral replication. In contrast, larger deletions or structurally deleterious point mutations in C-terminally adjacent sequences predicted to harbor a helical region abolished particle egress and Gag - Env protein interaction. Pull-down assays, using proteins of mammalian and prokaryotic origin, support the previous hypothesis of a direct interaction of both PFV proteins without requirement for cellular cofactors and suggest a potential direct contact of Env through this N-terminal Gag domain. Furthermore, analysis of point mutants within this domain in context of PFV vector particles indicates additional particle release-independent functions for this structure in viral replication by directly affecting virion infectivity.

CONCLUSIONS: Thus, our results demonstrate not only a critical function of an N-terminal PFV Gag motif for the essential capsid - glycoprotein interaction required for virus budding but also point out additional functions that affect virion infectivity.

Details

Original languageEnglish
Pages (from-to)45
JournalRetrovirology
Volume10
Publication statusPublished - 25 Apr 2013
Peer-reviewedYes

External IDs

PubMedCentral PMC3667135
ORCID /0000-0002-0320-4223/work/150885036
Scopus 84876993949

Keywords

Keywords

  • Gene Products, env/chemistry, Gene Products, gag/chemistry, Humans, Protein Binding, Protein Interaction Domains and Motifs, Spumavirus/physiology, Virulence, Virus Attachment, Virus Release