The Champion group is primarily interested in developing and exploiting novel approaches to identify and characterize the components of secreted proteins from virulent microorganisms. We heavily utilize the 'awesome power of genetics' coupled with state-of-the art quantitative proteomics to enrich, identify and quantify the proteins responsible for biological phenotypes. We have ongoing projects in pathogenic mycobacteria, protein translation in E. coli through the PTRN, and quantitative protein secretion measured using capillary electrophoresis. One example is described below.
Mycobacteria, the causative agent of tuberculosis, like most organisms secretes proteins for biochemical functions. Secreted proteins are a proteome of 'target'-enriched material which contains virulence-factors, antigenic-determinants, and targets for treatment/detection. EsxA and EsxB (ESAT-6 and CFP10) are essential virulence factors exported by mycobacteria and other Gram positive pathogens. Identification of proteins that are required for effective synthesis and secretion of these crucial virulence determinants has been hindered by a lack of saturating genetic screens; high-throughput biochemical detection, and accurate quantification of disease phenotypes. We designed orthogonal antibody-free assays using a slew of proteogenetic approaches to comprehensively dissect the individual contribution of gene products towards a functioning disease secretion system (ESX-1) in pathogenic mycobacterium. This framework is highly extensible to the analysis of other pathogen and protein secretion systems, and has uncovered novel genes, pathways, and crosstalk among secretion systems.
