Development of a novel method for discovery of bioactive natural products.
Since the dawn of medicine, compounds derived from natural sources have been used as therapeutic agents. The continued exploration of the small molecule repertoire of many organisms, such as plants and microbes, is bound to prove fruitful for the discovery of novel bioactive compounds (ACS Chem. Biol. 2010, 5, 639-653). However, a major roadblock to the identification of pharmacologically active natural products is purification, as they are generally present as minor components of biological extracts. Current strategies facilitate enrichment based on a restricted set of separation mechanisms that are dependent upon physical properties such as solubility or size. To produce a separation strategy that provides a significant improvement over existing techniques, a method that employs enrichment principles that are independent of physicochemical properties must be devised. Accordingly, my research group is developing an innovative technology that separates natural products based upon a distinct and orthogonal chemical property: functional group composition (Figure 1; Chem. Sci. 2011, 2, 760-764).
To accomplish this goal, we utilize a reversible tagging strategy that covalently captures small molecules, enabling their chemoselective enrichment, followed by release of the unaltered chemical structures. These “capture and release” tags, called reversible enrichment tags, purify specific classes of natural products from complex biological preparations (Figure 2). Following enrichment, compounds are liberated using conditions that do not interfere with the structural integrity of the molecules or subsequent bioassays. This method allows us to explore and harness the immense diversity of nature’s molecular repertoire with unprecedented scope and depth to identify compounds with antibacterial activity.
What types of methods might you learn/use on this project?Organic synthesis, chromatography, mass spectrometry, structure elucidation (NMR, MS, etc.), high-throughput screening and bioassay development.
Assembly of biochemical networks that can be targeted to combat bacterial pathogenesis.
With the advent of the “age of antibiotics” in the 1940s, many believed that we had conquered these dangerous microbes. However, it quickly became apparent that the ability of bacteria to evolve resistance had been sorely underestimated. My research group utilizes an integrated molecular profiling system, including innovative metabolomic and functional proteomic methods, to examine biochemical pathways whose function may be important for disease pathogenesis and the development of new antibiotics.
We are using the metabolomics profiling technology, Metabolite Enrichment by Tagging and Proteolytic Release (METPR; Nat. Methods, 2007, 4, 429-435; J. Am. Chem. Soc. 2007, 129, 15780-15782), to identify compounds associated with bacterial pathogenesis. This method utilizes chemical tags to facilitate the enrichment of many classes of metabolites (Figure 3 and 4). To identify enzymes that play key metabolic roles in pathogenesis, we are conducting functional proteomic analysis of enzyme activities using activity-based protein profiling (ABPP). ABPP utilizes active site-directed probes to selectively label active enzymes, but not their inactive forms. These studies will lead to a more comprehensive understanding of bacterial pathogenesis and could provide novel therapeutic targets.
What types of methods might you learn/use on this project?Proteomics, metabolomics, organic synthesis, mass spectrometry, molecular modeling, protein expression/purification, microbiology and biochemistry.
