Recombinant Escherichia coli RNA polymerase sigma factor rpoS (rpoS) is produced in an E. coli expression system, corresponding to the full-length protein from amino acids 1 to 330. This product is tag-free and shows a purity level of greater than 85%, as verified by SDS-PAGE analysis. Designed for research use only, it appears well-suited for studies requiring high-quality recombinant protein without tag interference.
The sigma factor rpoS serves as a key component of the RNA polymerase holoenzyme in Escherichia coli. It plays what seems to be a crucial role in the transcriptional response to various stress conditions. Its primary function involves regulating genes associated with the stationary phase and stress response, which makes it a significant focus in bacterial gene expression and adaptive mechanisms research.
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.
1. In Vitro RNA Polymerase Reconstitution Assays
This recombinant RpoS sigma factor can be used to reconstitute functional RNA polymerase holoenzyme complexes in vitro by combining it with purified E. coli RNA polymerase core enzyme. Reconstituted complexes like these would enable researchers to study the specific promoter recognition and transcription initiation properties of RpoS-containing RNA polymerase. The full-length protein (1-330aa) appears to retain all functional domains necessary for core enzyme binding and promoter recognition. These assays can help elucidate the molecular mechanisms of stress response gene regulation in E. coli.
2. Promoter Binding Specificity Studies
The purified RpoS protein can be used in electrophoretic mobility shift assays (EMSA) or surface plasmon resonance experiments to characterize its binding affinity and specificity to various E. coli promoter sequences. Researchers may systematically test different promoter variants to map the DNA sequence requirements for RpoS recognition. This application would likely advance understanding of the RpoS regulon and help identify novel target genes under stress response control.
3. Protein-Protein Interaction Analysis
This recombinant protein serves as a valuable tool for studying interactions between RpoS and other cellular proteins involved in transcriptional regulation or sigma factor competition. Pull-down assays, co-immunoprecipitation experiments, or yeast two-hybrid screens can be performed to identify novel RpoS-interacting partners. The tag-free nature of this protein eliminates potential artifacts from affinity tags that might interfere with native protein interactions.
4. Antibody Development and Validation
The purified full-length RpoS protein can be used as an immunogen for generating specific antibodies against the E. coli stress response sigma factor. It also serves as a positive control and standard for validating the specificity and sensitivity of existing anti-RpoS antibodies in Western blotting, immunofluorescence, or ELISA applications. The high purity (>85%) suggests minimal cross-reactivity with other sigma factors during antibody characterization.
5. Structural and Biophysical Characterization
This recombinant protein provides material for detailed structural studies using techniques such as X-ray crystallography, NMR spectroscopy, or cryo-electron microscopy, either alone or in complex with RNA polymerase core enzyme and DNA. Biophysical analyses including circular dichroism spectroscopy, analytical ultracentrifugation, or dynamic light scattering can be performed to characterize protein folding, stability, and oligomerization states. Studies like these would contribute to understanding the molecular basis of sigma factor function and regulation.
