A two-dimensional proteome map of Shigella flexneri.

Shigella flexneri is a Gram-negative facultatively intracellular pathogen responsible for bacillary dysentery in humans. In this study, extracellular proteins from the culture medium and whole cell proteins in cellular extracts of S. flexneri 2a strain 2457T were examined by two-dimensional (2-D) gel electrophoresis using immobilized pH gradient (IPG) technology. Proteins were identified by matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) in combination with Mascot search program. In total, among the 488 proteins spots processed, 388 proteins were identified. The identified proteins represented 169 genes. By comparing results of Mascot search against databases of Escherichia coli and genomes of S. flexneri 2a, one S. flexneri-specific protein was identified and one possible gap was found in 2457T genome sequences. Although this proteome map is still incomplete, it is already a useful reference for future studies involving pathogenicity, vaccine development, design of novel antibacterial drugs, etc. Proteome maps and a table of all identified proteins are available on the internet at www.proteomics.com.cn.