A useful epitope tag derived from maltose binding protein.

Area of Science:

• Biochemistry
• Molecular Biology
• Protein Engineering

Background:

• Maltose binding protein (MBP) is widely used as an affinity and solubility tag in recombinant protein expression.
• The monoclonal antibody B48 exhibits high specificity for MBP, with no cross-reactivity to other proteins in Escherichia coli lysates.
• This specificity suggests the presence of a unique epitope on MBP suitable for protein purification and visualization.

Purpose of the Study:

• To identify and characterize the specific epitope on maltose binding protein (MBP) recognized by the B48 antibody.
• To engineer a minimal peptide tag based on the identified epitope for use in recombinant protein applications.
• To assess the utility of the engineered tag for purification and visualization of proteins expressed in E. coli.

Main Methods:

• Co-crystal structure determination of MBP bound to the B48 antibody.
• Identification of critical amino acids involved in the antibody-MBP binding interaction.
• Engineering of glutathione S-transferase (GST) fusion proteins with various MBP fragments.
• Mutational engineering to stabilize and minimize the epitope.

Main Results:

• Four critical amino acids of MBP were identified as essential for B48 antibody binding.
• The smallest functional fragment of MBP recognized by the B48 antibody was determined through GST fusion experiments.
• A minimized 14-amino acid tag was successfully engineered by stabilizing the epitope through mutational engineering.

Conclusions:

• A novel, minimal 14-amino acid epitope derived from maltose binding protein (MBP) has been identified.
• This engineered epitope, recognized by the B48 antibody, serves as an effective purification and visualization tag for recombinant proteins.
• The findings provide a valuable tool for enhancing recombinant protein expression and purification strategies in E. coli.