Recombinant Enterobacter aerogenes Methyl-accepting chemotaxis serine transducer (tse)
Product Specs
Note: While we prioritize shipping the format currently in stock, please specify your format preference in order notes for customized fulfillment.
Note: Standard shipping includes blue ice packs. Dry ice shipping requires prior arrangement and incurs additional charges.
The specific tag type is determined during production. If you require a particular tag, please specify this in your order; we will prioritize fulfilling your request.
Target Background
This protein functions as a receptor for the attractant L-serine and related amino acids. It acts as a chemotactic signal transducer, responding to environmental attractant and repellent concentration changes. This transduction process facilitates sensory adaptation by modulating methylation levels. Attractants increase methylation, while repellents decrease it, with CheR methyltransferase adding methyl groups and CheB methylesterase removing them.
KEGG: eae:EAE_15535
STRING: 1028307.EAE_15535
Q&A
Basic Research Questions
-
What is the methyl-accepting chemotaxis serine transducer (tse) in Enterobacter aerogenes?
The tse gene in Enterobacter aerogenes encodes a methyl-accepting chemotaxis protein that functions as a transmembrane receptor for serine. This transmembrane protein consists of a periplasmic receptor domain and a cytoplasmic signaling domain. The tse (taxis to serine) gene of E. aerogenes complements an E. coli tsr mutant, demonstrating its functional role in mediating chemotactic responses to serine . Methyl-accepting chemotaxis proteins are one of the first components in sensory excitation and adaptation responses in bacteria, allowing them to detect specific chemicals in their environment and alter their swimming behavior accordingly .
-
How does the structure of methyl-accepting chemotaxis proteins relate to their function?
Methyl-accepting chemotaxis proteins consist of three distinct domains:
| Domain Type | Location | Function |
|---|---|---|
| Periplasmic ligand-binding domain | Outside the cell membrane | Detection of specific chemoattractants/repellents |
| Transmembrane segments | Spanning cell membrane | Signal transmission across membrane |
| Cytoplasmic domain | Inside the cell | Signal transduction and methylation sites |
The periplasmic domain structure comprises a four-helical bundle with a left-handed twist that is either closed or partly opened. The amino acid sequence variations in this domain reflect different ligand specificities . When a ligand (e.g., serine) binds to the periplasmic domain, it causes a conformational change that transmits a signal across the membrane to the cytoplasmic domain. This signal then initiates a cascade that ultimately affects flagellar rotation, causing the bacterium to either continue swimming in the same direction or tumble and reorient .
-
How is the tse gene organized genetically in Enterobacter aerogenes?
In Enterobacter aerogenes, the tse gene exists within a chemotaxis gene cluster. Sequence analysis of 5 kilobases of E. aerogenes DNA revealed that the tse and tas (taxis to aspartate) genes are arranged in one operon, unlike their counterparts tsr and tar in E. coli which exist separately . The genetic organization includes:
-
A 3' fragment of the cheA gene
-
The cheW gene
-
The tse gene
-
The tas gene
-
A 5' fragment of the cheR gene
This operon organization suggests coordinated expression of these chemotaxis genes, which differs from the arrangement in E. coli and suggests potential differences in regulation .
-
What are the similarities and differences between tse in E. aerogenes and similar genes in other enteric bacteria?
The tse gene in Enterobacter aerogenes shows significant homology with chemotaxis genes in other enteric bacteria, but with distinctive differences:
| Feature | E. aerogenes (tse) | E. coli (tsr) | Comparison |
|---|---|---|---|
| Function | Serine chemotaxis | Serine chemotaxis | Similar function |
| Genetic organization | In operon with tas | Separate from tar | Different organization |
| Periplasmic domain | Homologous to Tsr | - | High similarity |
| Cytoplasmic domain | Similar to E. coli/S. typhimurium | - | High conservation |
The cytoplasmic domains of Tse and Tas are very similar to those of E. coli and S. typhimurium transducers, suggesting conservation of signaling mechanisms. The periplasmic domain of Tse is homologous to that of Tsr, but the periplasmic domains of Tas and Tar are much less similar, indicating evolutionary divergence in substrate recognition .
-
What is the role of methylation in chemotaxis protein function?
Methyl-accepting chemotaxis proteins undergo reversible methylation at specific glutamate residues in their cytoplasmic domains. This methylation is catalyzed by the methyltransferase CheR and removed by the methylesterase CheB. The addition of attractant to Bacillus subtilis cells causes an increase in labeling of methyl-accepting chemotaxis proteins, indicating enhanced turnover of methyl groups .
This turnover of methyl groups functions as an excitatory signal and continues throughout the adaptation period, allowing the bacterium to adjust its sensitivity to the current chemical environment .
