An Update Proteome Reference Map Of Shigella Flexneri 2a Strain 2457T And Functional Analysis

Shigella spp.can cause a disease called shigellosis in humans, an infection of colonic epithelial cells characterized by abdominal cramps, diarrhea, and fever. Shigella flexneri is responsible for the majority of cases of endemic dysentery prevalent in developing countries where sanitation is poor. Because few are known about Shigella's pathogenesisa, noideal and effective vaccine has been developed till now. So it is important for vaccine to update proteome reference map of Shigella flexneri 2a strain 2457T.In this study, proteins from the whole intracellular extracts of S. flexneri 2a strain 2457T grown at the temperature of 37 or 30 oC and at the stationary or logarithmic stage were seperated by two-dimensional gel electrophoresis (2-DE). Protein spots were excised from gels, in-gel digested followed by identification by using matrix-assisted laser desorption / ionization-time of flight / time of flight (MALDI-TOF /TOF) in combination with Mascot search program and function analysis of the proteins, The data were revealed as:1) The best result for protein separation was obtained in the gels by using IPG strips of variant pH gradient.2) Eight hundred and sixty nine spots were excised from gels and 755 spots representing 588 protein entries were identified, including 70 hypothetical proteins. The identified proteins composed of 13.6% of the predicted ORFs in the genome of S. flexneri 2a strain 2457T. Isoelectric point values and molecular weight estimated by gel electrophoresis were matched closely to their predicted values, but some discrepancies exist. This suggested that post-translational protein modifications might be common in S. flexneri 2a strain 2457T.3) Most identified proteins were involved in TCA cycle, glycolysis, purine, and pyrmidine metabolism.4) By studying the different proteins by comparative proteomics and locating the different proteins in metabolism pathway, we found that most of those temperature-induced proteins at 37 oC were virulence-related proteins, heat shock proteins and chaperone proteins. Most proteins involved in purine and pyrmidine metabolism were down-regulated at 37 oC.In stationary phage,the down-regulated proteins were some enzymes involved in TCA cycle and the process translation; the up-regulated proteins were involved in glycolysis and oxidation recovery.