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Construction of a recombinant bacterial human CD4 expression system producing a bioactive CD4 molecule
D E McCallus1, K E Ugen, A I Sato
1Wistar Institute of Anatomy and Biology, Philadelphia, Pennsylvania.
Viral Immunology
|January 1, 1992
Summary
Researchers engineered a novel bacterial expression vector (pDABL) for producing functional CD4 protein. This system enables efficient refolding and screening of CD4 interactions, including with HIV-1 gp120, facilitating further biological studies.
Area of Science:
- Immunology
- Molecular Biology
- Biotechnology
Background:
- CD4 protein on helper T lymphocytes is crucial for immune responses and serves as the cellular receptor for human immunodeficiency virus (HIV).
- Soluble CD4 inhibits HIV infection in vitro, highlighting its therapeutic potential.
- Bacterial production of CD4 is desirable for research but requires proper refolding for biological activity.
Purpose of the Study:
- To engineer a bacterial expression system for producing biologically active CD4.
- To facilitate the correct folding of bacterially expressed CD4 protein.
- To develop a screening method for molecules interacting with the CD4 external domain.
Main Methods:
- Engineered an external domain construct of the CD4 gene into the pDABL vector, incorporating the pelB leader peptide for bacterial folding.
- Utilized monoclonal antibodies recognizing conformational epitopes of CD4 to screen bacterial colonies.
- Tested binding of recombinant HIV-1 gp120 to bacterial colonies expressing CD4.
Main Results:
- Bacterial colonies containing the pDABL/CD4 vector showed binding to conformation-specific anti-CD4 monoclonal antibodies.
- Recombinant gp120 specifically bound to bacterial colonies expressing the recombinant CD4 molecule.
- The system demonstrated a simple screening mechanism for CD4-binding molecules.
Conclusions:
- The pDABL vector facilitates the bacterial production and correct folding of the CD4 external domain.
- This system provides an efficient method for screening molecules that interact with CD4, including viral proteins.
- The approach supports the large-scale production of biologically active proteins in bacteria.