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Conformational Evaluation of HIV-1 Trimeric Envelope Glycoproteins Using a Cell-based ELISA Assay
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Functional characterization of the N termini of murine leukemia virus envelope proteins

C W Lu1, M J Roth

  • 1Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, New Jersey 08854, USA.

Journal of Virology
|April 5, 2001
PubMed

Insights

Investigating the murine leukemia virus (MuLV) envelope (Env) protein's N terminus revealed critical regions affecting viral entry. Specific N-terminal sequences from ecotropic Moloney MuLV (M-MuLV) impact post-binding steps and overall viral infectivity.

Area of Science:

  • Virology
  • Molecular Biology
  • Structural Biology

Background:

  • The murine leukemia virus (MuLV) surface (SU) protein is crucial for viral entry.
  • Understanding the N-terminal domain's role is key to dissecting MuLV infection mechanisms.

Purpose of the Study:

  • To functionally characterize the N-terminal region of the MuLV Env protein.
  • To identify specific amino acid sequences influencing receptor binding and post-binding events.

Main Methods:

  • Construction and analysis of five chimeric MuLV envelope (Env) proteins.
  • Exchanging N-terminal sequences between amphotropic 4070A and ecotropic Moloney MuLV (M-MuLV).
  • Assessing viral titers, Env expression, and receptor binding of chimeric viruses.

Main Results:

  • Chimeric Env proteins with exchanged N-terminal sequences showed varied functional outcomes.
  • The first 28 amino acids of ecotropic M-MuLV Env supported receptor binding but caused a 5- to 45-fold reduction in viral titer, indicating a post-binding block.
  • Further N-terminal exchanges beyond 28 amino acids led to defective protein expression.
  • In a specific chimeric backbone (AE4), the initial 17 amino acids of ecotropic Env significantly enhanced viral titer, suggesting functional coordination.

Conclusions:

  • The N terminus of the MuLV Env protein plays a critical role in viral infectivity.
  • Specific N-terminal sequences dictate post-binding efficiency and overall viral entry.
  • Functional coordination exists between the N- and C-termini of the SU protein and potentially transmembrane proteins.

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