Part:BBa_K2543001
GAM1 promoter / pSB1C3
GAM1 is an inducible promoter from mosquitoes and regulated by Toll signaling in the mosquito defense system. The promoter drives the immune responsive antimicrobial peptide (AMP), Gambicin to kill both Gram-positive and Gram-negative bacteria. And it can control Dengue virus infection and malaria parasite through Toll pathway. It works both in mosquitoes (e.g, Anopheles gambiae, Aedes aegypti, Aedes albopictus, etc.) and insect cell lines (e.g, Drosophila S2 cells, Aag2 cells, C6/36 cells, etc.)
Mosquito Toll-AMP Signaling
Mosquito GAM1 promoter is one of the AMP promoters driven by Toll signaling and activated by mosquito-borne pathogens
GENE CLONING
GAM1 Promoter Cloned from the Mosquito Genomic DNA
The DNA fragment of GAM1 promoter was amplified from gDNA of Aedes aegypti by PCR. The PCR products were cloned onto pSB1C3 vector and the sequence was confirmed by sequencing.
FUNCTIONAL ASSAY
To test the function of GAM1 promoter, the part was assembled with GFP and polyA (Part: BBa_K2543005, GAM1-GFP-polyA/pSB1C3)
Green Fluorescence Observed by E. coli Challenge
To test the function of the devices, C6/36 cells were transfected with the plasmid vectors. And the mosquito cells were challenged with bacteria on 2 days after transfection.
GFP positive cell with GAM1-GFP-polyA / pSB1C3 challenged with E. coli
GFP with GAM1-GFP-polyA/pSB1C3 induced by both Gram (-) E. coli and Gram (+) B. subtilis bacteria
GFP signal dose-dependently increased with bacteria concentrations
To verify the application of GAM1 promoter as a biosensor to measure the amounts of pathogens, E. coli at various concentrations were added onto the mosquito cells transfected with the GAM1-GFP-polyA / pSB1C3
Taken together, we created a GFP reporter system driven under AMP promoter by Toll signaling. The expression of GFP can be induced by bacteria in a dose-dependent manner. The green fluorescence observed under microscope further proved the concept of GE mosquito cells as a pathogen surveillance tool.
Glowing mosquito with GAM1-GFP reporter and bacteria
To demonstrate in adult mosquitoes, we collaborated with iGEM Team NCHU_Taichung to microinject DNA into Aedes aegypti. We prepared the plasmid of GAM1-GFP-polyA / pSB1C3 and heat-killed E. coli. A member who works in Entomology Department of National Chung Hsing University take us to the mosquito lab and helped us inject the materials to the midgut of Aedes aegypti.
GFP positive cell with GAM1-GFP-polyA / pSB1C3 challenged with E. coli
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25COMPATIBLE WITH RFC[25]
- 1000COMPATIBLE WITH RFC[1000]
References
1. PNAS (2001) Gambicin: a novel immune responsive antimicrobial peptide from the malaria vector Anopheles gambiae.
2. Insect Mol Biol. (2007) Regulated expression of microinjected DNA in adult Aedes aegypti mosquitoes
3. PLoS Pathog. (2008) The Aedes aegypti toll pathway controls dengue virus infection.
4. Front Cell Infect Microbiol. (2017) Regulation of Antimicrobial Peptides in Aedes aegypti Aag2 Cells
5. PNAS (2017) Insect pathogenic fungus interacts with the gut microbiota to accelerate mosquito mortality.
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