Team:Edinburgh/Plan/Beta-Carotene

From 2008.igem.org

Revision as of 17:47, 29 October 2008 by Andhi (Talk | contribs)

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

Figure 1: Details of the β-carotene synthesis pathway, including structures and genes involved.
  1. Geranyl diphosphate synthase (crtE) converts the substrates farnesyl diphosphate and isopentyl diphosphate into geranyl geranyl diphosphate.
  2. Geranyl geranyl diphosphate is then converted into phytoene by phytoene synthase (crtB).
  3. Lycopene is produced from phytoene by phytoene desaturase (crtI).
  4. 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-deoxyxylulose-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

Edinburgh-Beta-carotene.jpg
In blue are the genes which we manipulated.