Recombinant Swarming motility regulation sensor protein rssA (rssA)
Description
Introduction to Recombinant Swarming Motility Regulation Sensor Protein RssA
The recombinant swarming motility regulation sensor protein RssA is a crucial component of the two-component signaling system in Serratia marcescens, a bacterium known for its swarming behavior. This system, comprising RssA and its response regulator RssB, plays a pivotal role in regulating swarming motility by acting as a negative regulator. The RssA protein is characterized by its sensor kinase activity, which involves the transfer of a phosphate group to RssB, thereby initiating a signaling cascade that modulates swarming behavior.
Biochemical Characteristics of RssA
RssA exhibits typical characteristics of sensor proteins, including several conserved blocks (H, N, D/F, and G) that are essential for its function. The H block contains a putative phosphorylation site at histidine 248, which is critical for the phosphotransfer reaction to RssB . Additionally, RssA is predicted to have two transmembrane domains in its N-terminal region, suggesting its anchorage to the cytoplasmic membrane.
Role in Swarming Motility Regulation
Swarming motility in S. marcescens is a complex process influenced by environmental factors and genetic regulation. The RssA-RssB system is activated to suppress premature swarming, ensuring that swarming occurs under optimal conditions. Mutations in rssA or rssB lead to precocious swarming, indicating their role as negative regulators . This regulation is crucial for the survival and spread of S. marcescens in various environments.
Phosphorelay Mechanism
The phosphorelay mechanism involves the transfer of a phosphate group from RssA to RssB. This process is essential for the activation of RssB, which then binds to specific DNA sequences to regulate gene expression. In vitro assays have shown that phosphorylated RssB binds to its own promoter region, demonstrating a negative autoregulation mechanism that controls the expression of the RssA-RssB system itself .
Table: Key Features of RssA and RssB
| Feature | RssA | RssB |
|---|---|---|
| Function | Sensor kinase | Response regulator |
| Phosphorylation Site | His-248 | Asp-51 |
| Conserved Domains | Blocks H, N, D/F, G | OmpR family conserved residues |
| Transmembrane Domains | Predicted N-terminal domains | None reported |
| Regulatory Role | Negative regulation of swarming | Negative autoregulation and regulation of target genes |
Table: Effects of Mutations on Swarming Behavior
| Mutation | Effect on Swarming |
|---|---|
| rssA mutant | Precocious swarming at higher agar concentrations and temperatures |
| rssB mutant | Similar precocious swarming phenotype as rssA mutant |
| rssA(H248A) mutant | Cannot complement the precocious swarming phenotype |
Product Specs
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Target Background
Recombinant Swarming motility regulation sensor protein rssA (rssA) is a member of the two-component regulatory system RssA/RssB, involved in regulating swarming motility. Saturated fatty acids have been shown to inhibit this process. RssA/RssB regulates cellular fatty acid composition, hemolysin production, and cell surface topography. Furthermore, RssA/RssB acts as a negative regulator for SlhBA activity and swarming initiation.
