Monalysin, a Novel ß-Pore-Forming Toxin from the Drosophila Pathogen Pseudomonas entomophila, Contributes to Host Intestinal Damage and Lethality
Figure 1
PSEEN3174 encodes a secreted protein, Monalysin, required for P. entomophila virulence.
(A) SDS-PAGE analysis of culture supernatants from wild type P. entomophila and the ΔgacA derivative. Proteins extracted from culture supernatants were loaded on a SDS-PAGE and stained with coomassie blue. The nature of proteins identified by MALDI-TOF analysis of tryptic fragments is shown on the right. (B) Survival analysis of wild-type Oregon adult flies following infection by feeding with the P. entomophila wild-type strain (Pe), the gacA-deficient strain (ΔgacA), the mnl deficient strain (Δmnl) the mnl-deficient strain carrying a plasmid expressing a wild-type copy of the monalysin gene (Δmnl-pPSVmnl), or carrying the plasmid pPSV35 without any insert (Δmnl-pPSV). UN: unchallenged. The Kaplan-Meier log rank test was used to determine statistical significance. Dashed brackets represent the significance between the different infections (***: p<0.001, ns: not significant). (C) Bacterial persistence in wild-type Oregon flies as the number of colony-forming-unit (cfu) per fly. After infection by the P. entomophila wild-type strain (Pe), the gacA-deficient strain (ΔgacA), the mnl deficient strain (Δmnl), the number of cfu per fly was determined at the indicated time point. (D and E )Time-course analysis of Diptericin expression measured by RT-qPCR in (D) guts (local) or (E) whole flies (corresponding to the systemic fat body expression). (F) Cell death quantification using acridine orange staining. Results represent the percentage of dead cells (acridine orange positive nuclei) in the midguts of flies infected for 16 hours with the indicated bacterial strains. Results represent the average of four independent experiments. Statistical analysis was performed using a Wilcoxon test, and different letters indicate significantly different values (P<0.05).