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M-PMV capsid transport is mediated by Env/Gag interactions at the pericentriolar recycling endosome

Jeffrey N Sfakianos1, Eric Hunter

  • 1Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

Traffic (Copenhagen, Denmark)
|September 6, 2003
PubMed

Insights

Retroviral Gag assembly relies on endocytic trafficking, not the secretory pathway. Env glycoproteins are essential for transporting Gag capsids from pericentriolar recycling endosomes.

Area of Science:

  • Virology
  • Cell Biology
  • Molecular Biology

Background:

  • Cytoplasmic transport of Gag molecules is crucial for retroviral assembly but poorly understood.
  • Mason-Pfizer monkey virus Gag assembles into capsids at a pericentriolar region.
  • Env protein is necessary for efficient Gag transport from the assembly site.

Purpose of the Study:

  • To investigate the mechanism of cytoplasmic Gag transport in retroviral assembly.
  • To determine the role of cellular trafficking pathways in Gag transport.
  • To elucidate the involvement of Env in the transport process.

Main Methods:

  • Investigated Gag localization and colocalization with cellular markers (ER, Golgi, TGN, transferrin, Rab11).
  • Utilized Brefeldin A (BFA) to assess secretory pathway involvement.
  • Employed Rab11 mutants to study the role of recycling endosomes.

Main Results:

  • Gag transport was not inhibited by BFA and did not colocalize with secretory pathway markers.
  • Gag colocalized with endocytosed transferrin and Rab11, indicating a role for recycling endosomes.
  • Rab11 mutants impaired Gag transport, confirming the role of recycling endosomes.
  • Env colocalized with Gag at the assembly site and is required for capsid export.

Conclusions:

  • Cytoplasmic Gag transport in Mason-Pfizer monkey virus assembly utilizes the endocytic pathway, specifically pericentriolar recycling endosomes.
  • The secretory pathway is not directly involved in Gag transport.
  • Retroviral Env glycoproteins are essential for initiating capsid export from the assembly site via endocytic trafficking.

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