Salmonella Research Today is a free monthly online journal that collates and summarizes the latest research about Salmonella, including details on salmonella typhimurium, food poisoning, infection, treatment.

Role of EAL-containing proteins in multicellular behavior of Salmonella enterica serovar Typhimurium.

Simm R, Lusch A, Kader A, Andersson M, Römling U

Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Box 280, SE-171 77 Stockholm, Sweden.

GGDEF and EAL domain proteins are involved in turnover of the novel secondary messenger cyclic di(3'-->5')-guanylic acid (c-di-GMP) in many bacteria. The rdar morphotype, a multicellular behavior of Salmonella enterica serovar Typhimurium characterized by the expression of the extracellular matrix components cellulose and curli fimbriae is controlled by c-di-GMP. In this work the roles of the EAL and GGDEF-EAL domain proteins on rdar morphotype development were investigated. Knockout of four of 15 EAL and GGDEF-EAL domain proteins upregulated rdar morphotype expression and expression of CsgD, the central regulator of the rdar morphotype, and partially downregulated c-di-GMP concentrations. More-detailed analysis showed that the EAL domain protein STM4264 and the GGDEF-EAL domain protein STM1703, which highly downregulated the rdar morphotype, have overlapping yet distinct functions. Another subset of EAL and GGDEF-EAL domain proteins influenced multicellular behavior in liquid culture and flagellum-mediated motility. Consequently, this work has shown that several EAL and GGDEF-EAL domain proteins, which act as phosphodiesterases, play a determinative role in the expression level of multicellular behavior of Salmonella enterica serovar Typhimurium.

Published 18 April 2007 in J Bacteriol, 189(9): 3613-23.
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