Recombinant Bordetella pertussis Serotype 3 fimbrial subunit (fim3) gets produced in an E. coli expression system and contains the complete mature protein sequence from amino acids 26-204. The protein carries an N-terminal 6xHis-SUMO tag, which appears to help with purification while likely boosting stability. SDS-PAGE analysis shows the product achieves greater than 90% purity—a level that should work well for most research needs.
Fim3 represents a structural protein that makes up part of the fimbriae in Bordetella pertussis, the bug behind whooping cough. These fimbriae seem crucial for how bacteria stick to things, and they probably play a major role in causing disease by helping the organism latch onto host cells. Getting a handle on fim3's structure and what it does may be key to figuring out how bacterial infections work and possibly creating new treatments.
Potential Applications
Note: The applications listed below are based on what we know about this protein's biological functions, published research, and experience from experts in the field. However, we haven't fully tested all of these applications ourselves yet. We'd recommend running some preliminary tests first to make sure they work for your specific research goals.
The recombinant B. pertussis Fim3 protein is expressed in E. coli with an N-terminal 6xHis-SUMO tag, covering the mature protein sequence (26-204aa) with >90% purity. As a bacterial fimbrial subunit, Fim3 naturally forms polymerized structures (fimbriae) and may require specific bacterial chaperones for correct folding. The SUMO tag generally enhances solubility and may improve folding efficiency in E. coli, but the protein's biological activity (specifically, its ability to polymerize or bind to receptors) remains unverified. While the high purity suggests good expression, the presence of the large SUMO tag (≈100 amino acids) may sterically hinder proper folding or intermolecular interactions essential for Fim3's native function. Without experimental validation, we cannot assume correct folding or bioactivity.
1. Antibody Development and Immunological Studies
This application is generally suitable. The recombinant Fim3 can serve as an immunogen for antibody production since antibodies often recognize linear epitopes. The His-SUMO tag facilitates purification. However, antibodies generated may not recognize conformation-dependent epitopes of the native, properly folded Fim3 in B. pertussis. Validate antibody specificity against native fimbriae or bacterial cells.
2. Protein-Protein Interaction Studies
Use with caution. The His-SUMO tag enables pull-down assays, but the large tag or potential misfolding may cause non-physiological interactions. If Fim3 requires proper folding/polymerization for native interactions (e.g., with host receptors or other fimbrial subunits), results may be misleading. SUMO protease cleavage can remove the tag, but folding post-cleavage is uncertain. Validate interactions with native Fim3 or genetic methods.
3. Biochemical Characterization and Stability Studies
This application is feasible for basic physicochemical properties (e.g., molecular weight, thermal stability). However, structural studies (e.g., circular dichroism) may reflect the SUMO-tagged protein's properties rather than native Fim3's. Data may not represent the natural fimbrial subunit's behavior, especially if polymerization capability is compromised. Interpret results in the context of the tagged protein.
4. Vaccine Research and Immunogenicity Assessment
This application requires significant modification. The His-SUMO tag is highly immunogenic and may dominate the immune response, reducing Fim3-specific immunity. Furthermore, a misfolded or non-polymerizing Fim3 may not elicit antibodies recognizing native fimbriae. Always remove the SUMO tag and verify the protein's native conformation before immunogenicity studies. Compare immune responses with native fimbriae or tag-free Fim3.
Final Recommendation & Action Plan
Prioritize experimental validation of the protein's folding and functionality before any functional applications. First, use SUMO protease to remove the tag and purify tag-free Fim3. Then, assess folding via circular dichroism (secondary structure) and native PAGE/Size Exclusion Chromatography (quaternary structure/polymerization). Validate functionality through receptor-binding assays or immunization studies, comparing with known native Fim3. For antibody production, proceed but characterize epitopes. For vaccine studies, use only tag-free, properly folded protein. Always include appropriate controls (e.g., native fimbriae) to ensure biological relevance.
