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Team:Edinburgh/Plan/Beta-Carotene
From 2008.igem.org
Contents |
β-carotene synthesis
β-carotene is produced from the products of glycolysis, as can be seen in the overview figure. We have concentrated on two areas of β-carotene for our project. The first involves transfering carotenoid synthesis genes from Pantoea ananatis, a member of the proteobacteria naturally capable of producing β-carotene. The second involves upregulating the glycolysis pathways in E. coli in order to concentrate more energy into making β-carotene.
Directly involved genes from P. ananatis
- Geranyl diphosphate synthase (crtE) converts the substrates farnesyl diphosphate and isopentyl diphosphate into geranyl geranyl diphosphate.
- Geranyl geranyl diphosphate is then converted into phytoene by phytoene synthase (crtB).
- Lycopene is produced from phytoene by phytoene desaturase (crtI).
- Finally, lycopene β-cyclase (crtY) cyclises lycopene to produce β-carotene.
See figure 1 for structure details.
Indirectly involved genes from E. coli
- 1-deoxyxylulose-5-phosphate synthase (dxs) catalyses synthesis of 1-deoxy-D-xylulose-5-phosphate from glyceraldehyde-3-phosphate and pyruvate, transferring these two substrates from the glycolysis pathway to the lycopene synthesis pathway (see overview). It has been identified as a rate limiting step. To overcome this we decided to make a dxs BioBrickTM in order to increase the gene copy number.
- (appY) encodes a transcriptional regulator related to anaerobic energy metabolism. It is not directly involved in the lycopene synthesis pathway, but co-expression of appY with dxs has been reported to produce 8x the amount of lycopene produced in the absence of these genes.
Overview
- In blue are the genes which we manipulated.
