Key Biological Components for Arsenic Biosensor System
Introduction
This page documents the key biological components used in our arsenic biosensor system. Each part has been carefully selected and characterized to ensure optimal performance in detecting arsenic contamination in environmental samples.
ArsR Protein
Functional Description
The ArsR protein, derived from Cupriavidus metallidurans CML2, is a regulatory protein associated with arsenic resistance in prokaryotes.
- In arsenic-free or low-arsenic environments, ArsR specifically binds to the promoter/operon (P/O) region of arsenic resistance operons (such as the ars operon), thereby inhibiting the transcription of downstream resistance genes (e.g., arsC, arsB, etc.)
- When arsenic (or certain heavy metals like Bi³⁺, Co²⁺) is present in the environment, ArsR first binds these metal ions, then undergoes a conformational change and dissociates from the P/O region
- This releases the inhibition on downstream genes, promoting the expression of resistance genes to counteract arsenic toxicity
Registry Information
| Numbers | Name | Type |
|---|---|---|
| BBa_256BG3UA | ArsR | Transcription Regulatory Factor |
ParsCML2 Promoter
Functional Description
The ParsCML2 promoter is derived from Cupriavidus metallidurans CML2 and drives the expression of the reporter gene sfGFP.
Registry Information
| Numbers | Name | Type |
|---|---|---|
| BBa_25RM3KEY | ParsCML2 | Promoter |
ParsCML2 is an inducible promoter located within an arsenic resistance operon of Cupriavidus metallidurans CML2, with its core functions as follows: In the absence of arsenic (or under low-arsenic conditions), the promoter/operator (P/O) region can bind to the ArsR protein, thereby repressing the transcription of downstream resistance genes (e.g., arsC, arsB). When arsenic (or certain heavy metals such as Bi³⁺ and Co²⁺) is present in the environment, ArsR undergoes a conformational change after binding to these metal ions, dissociates from the P/O region, relieves the repression, and enables the expression of resistance genes to counteract arsenic toxicity.
GFP1-10 Protein
Functional Description
GFP1-10 protein is the N-terminal long fragment of GFP, forming the primary structural framework of GFP.
- GFP1-10 protein belongs to a class of GFP self-assembly-dependent split fragments characterized by "fluorescence complementation"
- Individual fragments exhibit no fluorescence
- Only when two fragments are brought into proximity by a target event (such as protein interaction) and self-assemble into a complete GFP do they emit green fluorescence
- This significantly reduces background interference from free fluorescent molecules, meeting the "precise quantification" requirements of biosensors
Registry Information
| Numbers | Name | Type |
|---|---|---|
| BBa_25PVXBRM | GFP1-10 | Reporter Gene |
GFP11 Protein
Functional Description
GFP11 protein is a C-terminal fragment of GFP.
- GFP11 protein belongs to a class of GFP self-assembly-dependent split fragments characterized by "fluorescence complementation"
- Individual fragments exhibit no fluorescence
- Only when two fragments are brought into proximity by a target event (such as protein interaction) and self-assemble into a complete GFP do they emit green fluorescence
- This significantly reduces background interference from free fluorescent molecules, meeting the "precise quantification" requirements of biosensors
Registry Information
| Numbers | Name | Type |
|---|---|---|
| BBa_252PDP57 | GFP11 | Reporter Gene |
RBS (sfGFP)
Functional Description
The RBS ribosome binding site mediates the binding of ribosomes to mRNA, thereby initiating the translation of the reporter gene sfGFP protein.
- Its sequence, distance from the AUG start codon, and other characteristics influence ribosome binding efficiency
- This in turn regulates sfGFP expression levels and fluorescence intensity
Registry Information
| Numbers | Name | Type |
|---|---|---|
| BBa_25YOH4M0 | RBS (sfGFP) | Ribosome Binding Site |
Component Integration
These biological parts work together in a coordinated system to detect arsenic contamination. The ArsR protein and ParsCML2 promoter form the core sensing mechanism, while the split GFP system (GFP1-10 and GFP11) provides a low-background reporting mechanism. The RBS ensures efficient translation of the reporter protein, completing the biosensor circuit.
System Advantages
- High Specificity: ArsR protein specifically responds to arsenic ions
- Low Background: Split GFP system minimizes basal fluorescence
- Environmental Adaptation: Components derived from environmental bacteria show better performance in field conditions
- Modular Design: Each part can be independently optimized or replaced