Regulation of gene exchange in bacterial outer membrane vesicles

Recent experimental work has revealed the ability of bacteria to produce and uptake extracellular vesicles. Such vesicle exchange enables cells to exchange biomolecules, including genetic material, which enables horizontal gene transfer between bacteria. Many of the biophysical mechanisms and parameters that control the production and uptake of such extracellular vesicles have not been explored.
We have systematically characterized how the molecular cargo and the donor and recipient cells influence the rate of gene exchange in vesicles. Gene transfer rates were measured for a library of plasmids with variable size, copy number, and origin of replication, revealing that although DNA was randomly loaded, plasmid properties such as the origin of replication strongly influence the rate of gene exchange. Cells can also regulate vesicle exchange rates by the release of exogenous molecules. In eukaryotic systems, vesicle exchange often requires molecules that modulate the large energetic cost associated with membrane restructuring during vesicle production and uptake. Our results demonstrate that many of bacterial compounds, including antimicrobial peptides, have a secondary role of regulating vesicle exchange at low concentrations.