Difference between revisions of "Part:BBa K3332009"

Latest revision as of 22:54, 27 October 2020

GOX-AIDA

We anchor GOX protein onto membranes through AIDA to catalyze the reaction of degradating glyphosate to form glyoxalic acid and AMPA. We use K880005 to construct the expression system and anchor GOX on the surface of E.coli.

Biology

        AIDA is an anchor protein from E. coli, which has been widely used in cell-surface display. GOX, also known as EcAKR4-1, is found in Echinochloa colona. It can decompose glyphosate into AMPA and glyoxylic acid. GOX is fused at C terminal with AIDA to get GOX-AIDA and we hope GOX can be displayed on the surface of E. coli.^[1][2]

Fig 1. Mechanism of GOX-AIDA on the surface of E. coli

Usage

        Here, we used BBa_K880005 to construct the expression system and obtained the composite part BBa_K3332054. We transformed the constructed plasmid into E. coli BL21 (DE3) to verify its successful expression.

Fig 2. Gene circuit of GOX-AIDA.

Characterization

1. Identification

        After receiving the synthesized DNA, restriction digestion was done to certify that the plasmid was correct, and the experimental results were shown in figure3.

Fig 3. DNA gel electrophoresis of restriction-digest products of GOX-AIDA-pSB1C3 (Xba I & Pst I sites).

2. Ability of degrading NADPH

        After transforming glyphosate into glyoxylic acid with the function of GOX, we use GRHPR, a Glyoxylate reductase from human liver, to reduce glyoxylic acid. GRHPR can convert glyoxylic acid when NADPH is consumed as cofactor. NADPH is a suitable target compound that can be detected by the signal of OD₃₄₀. And when NADPH is consumed, OD₃₄₀ declines.

        We mixed glyphosate solution, NADPH solution, purified GRHPR protein dissolved in Tris-HCl(pH=7.5) and bacteria solution carrying GOX-AIDA. Then, we immediately detected OD₃₄₀ by using TECAN^® Infinite M200 Pro to see the effect of GOX fused with anchor protein.

        When using bacteria carrying GOX-AIDA, we successfully found OD₃₄₀ decrease as time went on. When using bacteria carrying J23100-RBS(BBa_K880005) and bacteria carrying GOX-Histag as control , we can see the decrease is less than the GOX-AIDA samples. The results prove that GOX-AIDA can be displayed on the surface and convert glyphosate as normal, which is shown in figure 5.

Fig 4. OD₃₄₀-Time curve of three fusion protein of GOX and anchor protein

References

1. ↑ Pan L, Yu Q, Han H, et al. Aldo-keto Reductase Metabolizes Glyphosate and Confers Glyphosate Resistance in Echinochloa colona[J]. Plant Physiol, 2019, 181(4): 1519-1534.
2. ↑ http://2016.igem.org/Team:TJUSLS_China

Sequence and Features