Complementation of a binding-defective retrovirus by a host cell receptor mutant

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Zhaohui Qian1, Hongzhe Wang, Cyril Empig

  • 1Department of Molecular Sciences, University of Tennessee Health Science Center, 858 Madison Ave., Room G01, Memphis, TN 38163, USA.

Journal of Virology
|May 14, 2004
PubMed

Insights

Ecotropic murine leukemia virus (MLV) entry depends on its envelope protein binding its receptor. Mutations in MLV Env and the mATRC1 receptor reveal close interaction, guiding future viral targeting strategies.

Area of Science:

  • Virology
  • Molecular Biology
  • Structural Biology

Background:

  • Ecotropic murine leukemia virus (MLV) entry into cells is mediated by the envelope protein (Env) interacting with the mouse cationic amino acid transporter 1 (mCAT1) receptor.
  • A specific mutation (D84K) in the MLV Env protein significantly impairs virus binding and infection.
  • Lysine 234 (K234) in mCAT1 has been identified as a residue influencing MLV binding and infection.

Purpose of the Study:

  • To investigate the functional interaction between the D84 residue in MLV Env and the K234 residue in mCAT1.
  • To elucidate the structural basis for the loss of ecotropic MLV infection caused by the D84K mutation in Env.
  • To determine the precise location of the receptor binding site on the MLV Env SU subunit.

Main Methods:

  • Site-directed mutagenesis of the MLV Env protein (D84K) and the mCAT1 receptor (rK234A, rK234D).
  • Infectivity assays using cells expressing modified mCAT1 receptors to assess D84K MLV infection.
  • Analysis of viral binding and infection complementation by receptor mutations.

Main Results:

  • Infection by D84K MLV increased significantly (3,000-fold for rK234A and 100,000-fold for rK234D) on cells expressing mutated mCAT1 receptors.
  • The receptor mutation rK234D showed stronger complementation of D84K virus infection than rK234A, suggesting a specific interaction.
  • Results indicate that D84 in MLV Env is in close proximity to rK234 in mCAT1 within the bound complex, with a likely direct interaction.

Conclusions:

  • The D84 residue in ecotropic MLV Env and the rK234 residue in mCAT1 receptor are in close proximity and likely interact directly.
  • Steric hindrance and charge repulsion contribute to the loss of infection by D84K/R MLV, but the loss of a specific D84-receptor interaction is also a factor.
  • Precise localization of the receptor binding site on the MLV Env SU subunit will enable the design of chimeric proteins for targeted viral entry.

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