Complex c-di-GMP Signaling Networks Mediate Transition between Virulence Properties and Biofilm Formation in Salmonella enterica Serovar Typhimurium
Figure 1
Individual GG(D/E)EF/EAL domain proteins affect S. typhimurium UMR1 invasion into HT-29 gastrointestinal epithelial cells.
Invasion of (A) GG(D/E)EF-domain protein mutants, of (B) EAL-domain protein mutants and (C) GG(D/E)EF-EAL-domain protein mutants relative to the wild type S. typhimurium UMR1. Strains were grown under invasion inducing conditions (standing culture, LB+0.3M NaCl) until O.D.600 0.6. HT-29 cells were infected for 1 h with 107 CFU and subsequently incubated for an additional hour with 100 µg/ml gentamicin to kill extracellular bacteria. ΔompR, negative control for invasion. Invasion % is defined as (invasion value of mutant/invasion value of wild type)*100, whereby for each strain invasion is calculated as (CFU recovered inside epithelial cells/CFU at time of inoculation). Bars show mean ± standard deviation from at least five independent biological experiments performed in two technical replicates. Statistical significance is indicated by *P<0.05; **P<0.01; ***P<0.001 as compared with wild type S. typhimurium UMR1 (WT).