Team:UCSF/Split Pathway


Violacein: A Path Divided

Today’s industries are increasingly reliant on the biological production of fuels, drugs, and other materials, bacteria among the foremost type of organism used. However bacterial production has its limits; large and complicated molecules impose a heavy metabolic burden on cells, and production is limited by the fitness cost, or the decreased health of the concerned organism.

These limitations can be circumnavigated by mimicking nature: getting two or more organisms to work together to produce one product.One way of doing this is splitting the metabolic pathway between two cells.

One such pathway is the violacein pathway, involving the five enzymes VioA-E. This particular pathway was chosen for our project due to the fact that violacein is a pigment and easily detected.

Violacein is produced in nature by Chromobacterium violaceum and is used commercially as dye, and also has anti-viral and anti-cancer properties. So while we use this for the sake of a model system, violacein production itself has its own merits.

Splitting the Violacein Pathway

Other iGEM teams have produced violacein or the green intermediate in the pathway by putting the whole pathway on one plasmid in one cell. We have split the pathway by placing half the pathway on a plasmid in one strain and the other half in a second strain. The intermediate is protodeoxyviolaceinic acid, or PVA. Our results have shown that PVA readily diffuses through both cell membranes.

What Violacein has been doing outside of 2012 UCSF iGEM

The 2009 Cambridge team used violacein as an indicator for biosensing in the E. chromi project.

The 2010 Slovenia team used the violacein pathway as a marker and measure of efficiency in the DNA-protein assembly concept.

The 2011 Cornell team attempted to produce violacein in vitro using their Biofactory microfluidic System.

The 2011 Johns Hopkins team used violacein as a proof of concept for their Combinatorial Yeast Expression cassette library.