Outer Membrane Vesicles from bacteria expressing the HlyF/CprA family of enzymes are more efficient at delivering their cargo into host cells

HlyF, a cytoplasmic short-chain dehydrogenase/reductase enzyme encoded by a virulence plasmid in Escherichia coli , and its ortholog CprA, encoded notably by the chromosome of Pseudomonas aeruginosa , drive the production of specific outer membrane vesicles (OMVs). These OMVs have been shown to have the unique abilities to disrupt autophagic flux and exacerbate inflammatory response in host cells. In this study, we demonstrate that these OMVs have improved cargo delivery efficiency through a clathrin-independent internalization pathway into host cells, by directly fusing with the plasma membrane of the host cell. These results reveal an uncovered role of the HlyF/CprA enzyme family in enhancing OMV function through a unique internalization pathway and unveil a novel mechanism driving OMV-mediated virulence.