Proteins differentially expressed by Shiga toxin-producing Escherichia coli strain M03 due to the biliar salt sodium deoxycholate.

Shiga toxin-producing Escherichia coli (STEC) can cause conditions ranging from diarrhea to potentially fatal hemolytic uremic syndrome. Enteropathogen adaptation to the intestinal environment is necessary for the development of infection, and response to bile is an essential characteristic. We evaluated the response of STEC strain M03 to the bile salt sodium deoxycholate through proteomic analysis. Cell extracts of strain M03 grown with and without sodium deoxycholate were analyzed by two-dimensional electrophoresis; the differentially expressed proteins were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Three proteins were found to be differentially expressed due to sodium deoxycholate. Glycerol dehydrogenase and phosphate acetyltransferase, which are involved in carbon metabolism and have been associated with virulence in some bacteria, were downregulated. The elongation factor Tu (TufA) was upregulated. This protein participates in the translation process and also has chaperone activities. These findings help us understand strategies for bacterial survival under these conditions.