摘要：SummaryTwo-partner secretion (TPS) is widespread in the bacterial world. The pore-forming TPS toxin ExlA ofPseudomonas aeruginosais conserved in pathogenic and environmentalPseudomonas. WhileP. chlororaphisandP. entomophiladisplayed ExlA-dependent killing,P. putidadid not cause damage to eukaryotic cells. ExlA proteins interacted with epithelial cell membranes; however, only ExlAPchinduced the cleavage of the adhesive molecule E-cadherin. ExlA proteins participated in insecticidal activity toward the larvae ofGalleria mellonellaand the flyDrosophila melanogaster.Evolutionary analyses demonstrated that the differences in the C-terminal domains are partly due to horizontal movements of the operon within the genusPseudomonas.Reconstruction of the evolutionary history revealed the complex horizontal acquisitions. Together, our results provide evidence that conserved TPS toxins in environmentalPseudomonasplay a role in bacteria-insect interactions and discrete differences in CTDs may determine their specificity and mode of action toward eukaryotic cells.Graphical abstractDisplay OmittedHighlights•ExlA is a two-partner secreted toxin conserved acrossPseudomonasspp.•EnvironmentalPseudomonasstrains encode ExlA with different cytotoxic activities•ExlA of environmentalPseudomonasstrains play a role in bacteria-insect interactions•ExlBAoperon shows a complex evolutionary history of horizontal gene transferGenetics; Microbiology
