Monalysin, a Novel ß-Pore-Forming Toxin from the Drosophila Pathogen Pseudomonas entomophila, Contributes to Host Intestinal Damage and Lethality
Figure 3
Monalysin encodes a cytotoxic protein secreted by P. entomophila.
(A) Survival analysis of wild-type Oregon adult flies after injection of various quantities of Monalysin or heat-inactivated (denaturated) Monalysin. (B and C) Cytotoxic effect of Monalysin on insect culture cell line S2. (B) Drosophila S2 cells and Spodoptera frugiperda Sf9 cells were treated with Monalysin (Final concentration = 100nM) and stained with a live-dead viability reagent. Living cells are stained in green with Calcein while dead cells are stained in red with Ethidium homodimer 1 (EthD1, red). (C) The loss of viability was quantified by measuring the release of lactate dehydrogenase (LDH) from S2 cells. (D) DNA fragmentation in S2 cells was monitored by ISNT (in situ nick translation). (E) Chromatin condensation on untreated and Monalysin treated S2 cells was examined by DAPI staining. Phase-contrast and fluorescence views of the same microscopic fields are shown. (−) untreated cells, (+) = cells treated with Monalysin 100nM.