Difference between revisions of "Part:BBa K1497016"

Revision as of 01:33, 18 October 2014

Constitutive naringenin producing operon

Naringenin is the main flavone from grapefruits. In plants, it is synthesized from tyrosine and is one of the central metabolites in the flavone biosynthesis. It is able to reduce oxidative stress and inhibit some P450 enzymes. One of these cytochrome P450 enzymes is involved in the degradation of caffeine and increases the effect of caffeine after the inhibition with naringenin. The biosynthesis of naringenin is encoded by four genes. The proteins expressed by these genes convert L-tyrosine to the bioactive enantiomer S-naringenin.

Figure 1 Reaction scheme of the naringenin producing operon. The substrate for the reaction is L-tyrosine. The substrate is metabolized to S-naringenin in four steps.

Usage and Biology

This part is a composite of four genes each with a strong RBS (BBa_B0034). 4-coumaryl ligase - 4-CL BBa_K1033001 Tyrosine ammonia lyase - TAL BBa_K1033000 Chalchone isomerase - CHI BBa_K1497100 Chalchone synthase - CHS BBa_K1497101 Together, these genes define the naringenin biosynthesis operon without a promotor. In addition of a promotor part the device is able to produce S-naringenin. This device is working in E. coli K and B strains.

iGEM TU Darmstadt 2014 :)

Figure 2 Genetic map of the naringenin operon with T7 promoter (BBa_K1497017). This device produces naringenin in E. coli BL21(DE3) in presence of the inductor IPTG .

Functional Parameters

The iGEM Team TU Darmstadt 2014 created the naringenin biosynthesis operon under the control of the T7 promoter BBa_I712074 and a strong constitutive promoter BBa_J23100, respectively. They measured the naringenin production after 16 h incubation time with the naringenin biosensor BBa_K1497020. The cell pellets from E. coli BL21(DE3) – pSB1C3-fdeR-gfp with and without T7-naringenin operon (BBa_K1497017) are shown in figure 3. Only the cells transformed with BBa_K1497017 exhibited GFP fluorescence. The Darmstadt team was also able to measure the GFP fluorescence quantitatively and calculated the production yield of both operons with the help of a calibration curve for the naringenin sensor (Figure 4). They calculated a concentration of 1.9 µM (BBa_K1497016) and 3 µM (BBa_K1497017) naringenin repectively.

iGEM TU Darmstadt 2014 :)

Figure 2 Cell pellets with and without T7-Naringenin operon from E. coli BL21(DE3)-pSB1C3-fdeR-gfp. The pellet containing the naringenin operon shows a GFP fluorescence under ultraviolet light.

Figure 1 Fluorescence of cells with and without the T7-naringenin operon BBa_K1497017 from E. coli BL21(DE3)-pSB1C3-fdeR-gfp and J23100-naringenin operon (BBa_K1497016) from E. coli Top10-pSB1C3-fdeR-gfp, respectively. E. coli BL21(DE3)-pSB1C3-fdeR-gfp without T7-naringenin operon showed no detectable fluorescence. Only in the cells with the functional operon is the GFP fluorescence measurable. The estimated yields are 3 µM for BBa_K1497017 and 1.9 µM for BBa_K1497016.

Sequence and Features

References

1. Fuhr UWE, Klittich K, Staib AH (1993) Inhibitory effect of grapefruit juice and its bitter principal , naringenin , on CYP1A2 dependent metabolism of caffeine in. Br J clin Pharmac 35:431–436.

2. Siedler S, Stahlhut SG, Malla S, et al. (2014) Novel biosensors based on flavonoid-responsive transcriptional regulators introduced into Escherichia coli. Metabolic engineering 21:2–8. doi: 10.1016/j.ymben.2013.10.011

3. Yamaguchi T, Kurosaki F, Suh D, et al. (1999) Cross-reaction of chalcone synthase and stilbene synthase overexpressed in Escherichia coli. 460:457–461.

4. Jez JM, Bowman ME, Richard A, Noel JP (2000) letters Structure and mechanism of the evolutionarily unique plant enzyme chalcone isomerase. 7: