My research is focused on metabolic engineering of the valine biosynthesis pathway with TAL effector proteins. We will use Systems Biology approaches to manipulate well-defined systems. For example, Escherichia coli can be engineered to increase valine production. The branched-chain amino acid, valine, is of particular importance in biomedicine and biotechnology. The biosynthetic pathway of branched-chain amino acids in E. coli is complex, consisting of parallel pathways and isozymes. In this pathway, the catalysis of threonine into 2-ketobutyrate is inhibited by isoleucine but activated by valine. Accumulation of valine stimulates production of the toxic compound, 2-ketobutyrate, through this reaction. Optimizing the E. coli pathway to increase valine production continues to be a challenge for this reason.
The standard method of analyzing network perturbation is with gene knockouts or through overexpression with transgenes. Will use an alternative, less pervasive method, artificial transcription factors (ATFs). ATFs are proteins that are designed to target specific DNA sequences and change gene expression. One particularly efficient family of ATFs includes the transcription activator-like effector (TALE) proteins. These proteins are engineered to bind a defined DNA sequence. ATFs can be used to make the necessary modifications to the valine biosynthesis pathway.
The long-term goal of my graduate studies is to create ATFs to modify the valine pathway and optimize its production. These results will be used to modify and improve our current model.