ARS | Publication request: Autoinducer AI-2 is involved in regulating a variety of cellular processes in Salmonella Typhimurium

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 26, 2007
Publication Date: April 13, 2008
Citation: Soni, K., Jesudhasan, P., Cepeda, M., Williams, B., Hume, M.E., Jayaraman, A., Russell, W.K., Pillai, S.D. 2008. Autoinducer AI-2 is involved in regulating a variety of cellular processes in Salmonella Typhimurium. Foodborne Pathogens and Disease. 5:147-153.

Interpretive Summary: Chemical signaling between cells is a known strategy that is used to change a variety of processes in bacteria and to coordinate activities of different cells in a population. Salmonella Typhimurium is known to possess such a chemical signal system called the LuxS/AI-2 system. We have investigated the role of LuxS/AI-2 system on S. Typhimurium using a protein detection technique to measure changes in protein production. Protein production in normal Salmonella Typhimurium was compared to that of a mutated Salmonella Typhimurium that did not make the chemical signal. Seven proteins were produced in the normal Salmonella Typhimurium compared to the mutated Salmonella Typhimurium. Thirteen more proteins were affected in the mutated Salmonella Typhimurium when grown with the chemical signal. An analysis of the proteins affected by the chemical signal revealed that a variety of bacterial processes affected, such as, metabolism, virulence, cell survival, and proliferation are affected. A better understanding of how the chemical signal affects Salmonella Typhimurium will help develop better intervention strategies against Salmonella Typhimurium. The data is of interest to researchers developing strategies to reduce or eliminated Salmonella Typhimurium invasion and colonization. Additionally, the data is of interest to researchers developing an understanding of bacterial cell-to-cell communication.

Technical Abstract: LuxS/AI-2 mediated cell signaling is a known strategy that modulates a variety of bacterial processes in prokaryotes. Salmonella Typhimurium is known to possess LuxS/AI-2 mediated cell signaling. Until now, the Lsr- ABC transporter system (LuxS- regulated) is the only known process controlled by this cell signaling system. We have investigated the role of LuxS/AI-2 system on S. Typhimurium regulon using a Two Dimensional Gel Electrophoresis (2DGE) based proteomics approach. Protein expression profiles of the wild type, luxS mutant, and luxS mutant strain supplemented with AI-2 were compared. Two-dimensional protein gels were used to study the protein expression patterns. Seven different proteins were differentially expressed when comparing the wild type and luxS mutant strains, whereas thirteen different proteins were differentially expressed when luxS mutant strain was supplemented with AI-2 molecules. All the seven protein spots that were differentially expressed between wild type and luxS mutant strain were also differentially expressed in luxS mutant strain when supplemented with AI-2. Protein PhoP involved in the two component regulatory system, PhoPQ, appears to be influenced by the presence of AI-2 molecules. A pathway analysis revealed that the LuxS/AI-2 mediated system influences a variety of bacterial processes such as metabolism, virulence, cell survival, proliferation etc in S. Typhimurium.