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The solution structure of the simian foamy virus protease reveals a monomeric protein

Maximilian J Hartl1, Birgitta M Wöhrl, Paul Rösch

  • 1Lehrstuhl für Struktur und Chemie der Biopolymere, Universität Bayreuth, 95440 Bayreuth, Germany.

Journal of Molecular Biology
|July 4, 2008
PubMed

Insights

Foamy viruses (FVs) express a unique protease-reverse transcriptase (PR-RT) protein. Unlike other retroviruses, simian FV PR-RT remains monomeric, suggesting a novel regulatory mechanism for viral assembly.

Area of Science:

  • Virology
  • Structural Biology
  • Biochemistry

Background:

  • Foamy viruses (FVs) differ from orthoretroviruses in their Pol polyprotein expression strategy.
  • FVs produce a protease-reverse transcriptase (PR-RT) protein from a dedicated transcript.

Purpose of the Study:

  • To investigate the structural and functional properties of the simian foamy virus (SIV) protease (PRshort) domain.
  • To determine if the PR-RT protein of SIV exists as a monomer or dimer.

Main Methods:

  • Recombinant expression of SIV PRshort in Escherichia coli.
  • Nuclear Magnetic Resonance (NMR) spectroscopy for structural determination.
  • Size exclusion chromatography and sedimentation analyses for assessing protein quaternary structure.

Main Results:

  • SIV PRshort was purified and structurally characterized as a stable monomer in solution.
  • NMR analysis revealed significant differences in the dimerization interface compared to other retroviral proteases, with flexible flap regions.
  • The complete SIV PR-RT protein was also found to be monomeric.

Conclusions:

  • The monomeric state of SIV PR-RT is likely a regulatory mechanism to control protease activity before viral assembly.
  • This monomeric state may prevent premature packaging issues within the virus.
  • Dimerization of PR-RT might be induced by interactions with viral or cellular factors.

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