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Overview Sensitivity Tuner --- Characterisation --- Modelling Colour Generators --- Carotenoids (Orange/Red) --- Melanin (Brown) --- Violacein (Purple/Green) The Future Safety

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Violacein Pigments

Background

Violacein Biosynthesis

The Violacein pigment is produced from L-tryptophan via a pathway involving five enzymes, VioA-E. This forms a purple colour which remains within the individual cell colonies. This synthesis pathway is shown below:

From August et al (2000).

The vioE is used in the step just after the vioB for the 1-2 shift of the indole ring. Sánchez et. al (2006)

Further, as module 5 is Aqua, expressing the genes under different promoters will allow us to produce at least two different colours. Sanchez suggests that removing vioD can produce a dark blue, while removing vio C produces a dark green. Our actual results showed that the ABDE construct produced a dark green pigment while the ABCE produced light green.

Vio Operon

Our VioA-E genes are from Chromobacterium voilaceum ATCC 12472 in the pPSX vio+ plasmid. This was kindly provided by John Pemberton; Department of Microbiology and parasitology, University of Queensland, Brisbane, Australia. (Sarovich & Pemberton (2007) Plasmid 57:306-313)

• pPSX sequence ID FJ422118
• vio gene cluster complete cds AB032799 and AF172851.

We aim to successfully express violacein in E. coli, to synthesize the violacein operon as a biobrick, and to manipulate the operon to produce the other two pigments.