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Differences in sequence-specific expression of two anti-arsonate Fabs in E. coli
D S Gill1, Y W Wong, M N Margolies
1Department Of Surgery, Massachusetts General Hospital, Charlestown, USA.
Biotechnology Progress
|October 23, 1997
Summary
Bacterial expression of antibody fragments can be challenging. Researchers found that specific mutations in the complementarity-determining regions of the heavy chain prevent good expression of antibody 36-71 Fab in E. coli.
Area of Science:
- Biotechnology
- Immunology
- Molecular Biology
Background:
- Monoclonal antibodies are valuable therapeutics, with bacterial hosts like E. coli offering potential for production.
- However, some antibody fragments (Fabs) exhibit poor expression in bacteria, limiting their therapeutic development.
- Understanding the reasons for differential expression is crucial for optimizing recombinant antibody production.
Purpose of the Study:
- To investigate the molecular basis for the differential expression of two homologous anti-arsonate antibody Fabs (36-65 and 36-71) in E. coli.
- To identify specific regions or residues responsible for the poor expression of antibody 36-71 Fab.
Main Methods:
- Comparative analysis of two homologous anti-arsonate antibodies (36-65 and 36-71) with differing expression levels in E. coli.
- Systematic investigation of factors influencing Fab expression, including host strain, induction, and temperature.
- Construction of hybrid Fabs by swapping heavy and light chains to localize expression defects.
- Site-directed mutagenesis to alter specific amino acid residues in the variable regions of antibody 36-71 Fab.
Main Results:
- Standard optimization strategies (e.g., temperature, induction, E. coli strain) did not significantly improve the expression of 36-71 Fab.
- The heavy chain was identified as the primary determinant of the poor expression of 36-71 Fab.
- Site-directed mutagenesis revealed that residues within the complementarity-determining regions (CDRs) of the heavy chain are responsible for the impaired expression, not framework residues.
Conclusions:
- The poor bacterial expression of antibody 36-71 Fab is attributed to specific amino acid residues within its heavy chain's complementarity-determining regions.
- These findings highlight the critical role of CDRs in successful recombinant antibody fragment production in E. coli.
- Targeted engineering of CDRs may be necessary to enhance the expression of poorly expressing antibody fragments.