Fig. 1: Secretion of NELs of Y. pestis Is T3SS Dependent.

a Bacterial strains of the wild type Y. pestis and various mutants were grown in TMH medium without calcium at 37 °C and proteins in culture supernatants and bacterial pellets were analyzed by immunoblotting with specific antibodies against YspE1, YspE2 or YopM. The bands labeled with “*” might come from some unknown complexes involved in YspE1/YspE2. b Y. pestis strain 201 were grown in TMH at 26 °C, or in TMH with or without calcium at 37 °C as indicated. Proteins in culture supernatants and bacterial pellets were analyzed as described in a. The image of a and b represents results from three independent experiments. c Y. pestis strain 201 or ΔyscI carrying the empty Cya reporter plasmid (201-Cya), or plasmids containing the N-terminal coding sequence of yspE1 (201- yspE1-Cya), yspE2 (201-yspE2-Cya) or yopM (201-yopM-Cya) fused with Cya gene were grown at 26 °C in LB and shifted to 37 °C for 2 h incubation prior to infection. HeLa cells were infected with above strains for different hours and adenylate cyclase activity in the lysate of the infected cells were analyzed. Triplicates samples were analyzed for each reporter strain and the averages with standard deviations were shown.