Myobacterium tuberculosis Phenylalanine Synthesis as a Novel Drug Target

PROJECT SUMMARY / ABSTRACT Metabolic pathways that Mycobacterium tuberculosis (Mtb) requires for growth in lab culture conditions and that are highly vulnerable to inhibition have been proposed as novel drug targets. Amino acid biosynthetic pathways represent promising drug targets because they are essential for Mtb growth but are absent in humans. However, we do not yet know which of these pathways Mtb requires during infection or how their inhibition influences susceptibility to existing antibiotics. The overall objective of this exploratory proposal is to determine the potential of phenylalanine (Phe) biosynthesis as a novel anti-tubercular drug target. The central hypothesis is that inhibition of Mtb Phe synthesis disrupts multiple central metabolic pathways to cause death of Mtb and enhance susceptibility to existing antibiotics. Preliminary data show that Mtb starved for Phe die in vitro and that a Phe auxotroph is rapidly cleared from acutely infected mice. Aim 1 will develop Mtb strains that conditionally express enzymes in the Phe biosynthesis pathway. These strains will be used in macrophage and mouse infection models to determine the extent to which Mtb requires Phe synthesis during infection and how Phe synthesis inhibition influences efficacy of existing anti-tubercular drugs. Aim 2 will use transcriptomic and metabolomic analyses of Phe-starved Mtb to identify the metabolic changes and stress responses induced upon inhibition of Phe synthesis. The proposed research is expected to be significant because it will establish Phe synthesis as a promising target for development of new drugs to treat tuberculosis and enable future high- throughput screens to identify small molecules that inhibit Phe synthesis.