Secretome Biomarkers for the Identification and Differentiation of Enterohemorrhagic and Enteropathogenic Escherichia coli Strains

The secreted proteins of the enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) are the most common cause of hemorrhagic colitis, which is a bloody diarrhea with EHEC infection that can often lead to lifethreatening hemolytic-uremic syndrome. We are employing a metaproteomic approach as an effective and complementary technique to the current genomic-based approaches. This metaproteomic approach will evaluate the secreted proteins associated with pathogenicity and utilize their signatures as differentiation biomarkers between EHEC and EPEC strains. Analysis of extract from EHEC O104:H4 resulted in the identification of a multidrug efflux protein that belongs to the family of fusion proteins, which are responsible for cell transportation. The experimental peptides identified lie in the region of the HlyD hemolysin secretion protein-D, which is responsible for transporting the hemolysin A toxin. Moreover, the taxonomic classification of EHEC O104:H4 showed the closest match with E. coli E55989, which is in agreement with genomic-sequencing studies that were done extensively on the aforementioned strain. Comparative proteomic calculations showed separation between EHEC O157:H7 and O104:H4 in replicate samples using cluster analysis. There were no reported studies that addressed the characterization of secreted proteins in various enhanced-growth media and utilized them as biomarkers for strain differentiation. The original document contains color images.