Basic residues in the Mason-Pfizer monkey virus gag matrix domain regulate intracellular trafficking and

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Elizabeth Stansell1, Robert Apkarian, Sarka Haubova

  • 1Department of Pathology and Emory Vaccine Center at Yerkes Regional Primate Research Center, Emory University, Atlanta, Georgia 30329, USA.

Journal of Virology
|June 29, 2007
PubMed

Insights

Basic amino acids on Mason-Pfizer monkey virus (M-PMV) matrix (MA) proteins are crucial for efficient viral release. Mutations altering these charges disrupt capsid transport and membrane association, affecting virus release efficiency.

Area of Science:

  • Virology
  • Molecular Biology
  • Cell Biology

Background:

  • Mason-Pfizer monkey virus (M-PMV) requires capsid transport to the plasma membrane for viral release.
  • The matrix (MA) protein of the Gag polyprotein has a positively charged surface near the membrane.

Purpose of the Study:

  • To investigate the role of basic amino acids in the M-PMV MA protein in intracellular transport and capsid-membrane interactions.
  • To determine how charge substitutions affect M-PMV release efficiency and capsid localization.

Main Methods:

  • Construction and analysis of M-PMV Gag mutants with single and double alanine substitutions of lysine and arginine residues in the MA protein.
  • Electron microscopy to visualize capsid localization and budding in mutant-expressing cells.
  • Single-round infectivity assays to assess the impact of mutations on viral progeny.

Main Results:

  • Most charge substitution mutants showed reduced viral release efficiency compared to wild-type M-PMV.
  • Mutants exhibited distinct intracellular transport defects, including accumulation in vesicles, arrest at the actin network, or cytoplasmic dispersal.
  • Some mutants accumulated capsids at the plasma membrane, while others were impaired earlier in transport.
  • Mutated virions that were released retained near-wild-type infectivity.

Conclusions:

  • Basic amino acids in the M-PMV MA protein are essential for proper capsid intracellular transport.
  • These residues play a critical role in mediating capsid association with the plasma membrane.
  • Charge substitutions in MA significantly impact the efficiency of M-PMV release, but not the infectivity of released virions.

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