Recombinant Campylobacter jejuni Flagellin B (flaB) is expressed in E. coli and includes the complete mature protein sequence from amino acids 2 to 575. The protein carries a C-terminal 6xHis tag that makes purification and detection more straightforward. SDS-PAGE analysis shows the product achieves greater than 85% purity, which appears to provide a reliable reagent for research work.
Flagellin B serves as a key structural component in bacterial flagella assembly—structures that C. jejuni needs for movement. The protein seems central to how these bacteria get around and may play an important role in how they cause disease and interact with their hosts. Understanding this protein could help researchers figure out bacterial movement patterns and possibly develop new ways to fight infections from this pathogen.
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.
Based on the provided information, the folding state and bioactivity of this recombinant FlaB protein are unknown and cannot be assumed. Flagellin is a complex protein that must fold correctly to form filament polymers and to be recognized by Toll-like receptor 5 (TLR5), which are its primary biological activities. Expression in E. coli, while a prokaryotic system, does not guarantee correct folding for a protein from another bacterium (C. jejuni). The C-terminal His-tag and the truncation (starting at residue 2) could potentially interfere with the precise conformational requirements for polymerization or receptor binding. The >85% purity confirms a lack of major contaminants but provides no evidence of a native, functional structure.
1. Antibody Development and Immunological Studies
This recombinant FlaB protein is suitable for use as an immunogen to generate polyclonal or monoclonal antibodies. The C-terminal 6xHis tag simplifies purification and can be used for screening. However, antibodies generated will primarily recognize linear epitopes. Their ability to bind the natively folded, polymerized flagellin in functional flagellar filaments is not guaranteed and would require separate validation. The protein can be used in ELISA to test antibody specificity, but this primarily assesses recognition of the denatured or linear antigen.
2. Protein-Protein Interaction Studies
The His-tagged FlaB protein can be used in pull-down assays to identify potential binding partners. However, a critical limitation is that any interactions detected are contingent upon the recombinant FlaB protein being correctly folded. This is particularly important for flagellin, as its native interaction partners are other flagellin monomers (for polymerization) and specific components of the export apparatus. If the protein is misfolded, negative results are meaningless, and positive results must be confirmed to be specific.
3. Biochemical Characterization and Comparative Studies
This recombinant FlaB protein is well-suited for basic biochemical characterization, such as molecular weight confirmation, thermal stability assays (e.g., by circular dichroism or differential scanning fluorimetry), and pH stability studies. It can serve as a standard for comparative analyses with other flagellins. This application is valid as it focuses on the protein's intrinsic physicochemical properties, which are largely independent of its complex native bioactivity.
4. In Vitro Flagellar Assembly Studies
This application is highly speculative and entirely dependent on the unverified correct folding and inherent self-assembly capability of the recombinant protein. The use of this protein in cell-free systems to study filament assembly presupposes that it is functional. The His-tag, especially at the C-terminus, which is critical for polymerization in many flagellins, may severely inhibit or prevent proper self-assembly. Therefore, this application should not be described as a given use but rather as a potential goal that is contingent on first demonstrating that the purified protein can polymerize under in vitro conditions.
Final Recommendation & Action Plan
The immediate and essential next step is to experimentally test the protein's bioactivity before embarking on functional studies. The most critical assays would be to determine if the protein can (i) polymerize into filaments observable by electron microscopy and (ii) activate TLR5 signaling in a reporter cell line. A positive result in either, especially polymerization, would validate its use for Applications 2 and 4. A negative result would limit its utility to Applications 1 (with the noted caveat about native conformation recognition) and 3 (biophysical characterization). Without this functional validation, data from assembly or interaction studies are highly likely to be inconclusive or misleading.
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