Genomic erosion and horizontal gene transfer shape functional differences of the ExlA toxin in spp.

Two-partner secretion (TPS) is widespread in the bacterial world. The pore-forming TPS toxin ExlA of is conserved in pathogenic and environmental . While and displayed ExlA-dependent killing, did not cause damage to eukaryotic cells. ExlA proteins interacted with epithelial cell membranes; however, only ExlA induced the cleavage of the adhesive molecule E-cadherin. ExlA proteins participated in insecticidal activity toward the larvae of and the fly Evolutionary analyses demonstrated that the differences in the C-terminal domains are partly due to horizontal movements of the operon within the genus Reconstruction of the evolutionary history revealed the complex horizontal acquisitions. Together, our results provide evidence that conserved TPS toxins in environmental play a role in bacteria-insect interactions and discrete differences in CTDs may determine their specificity and mode of action toward eukaryotic cells.