[S1-6] Applying single cell imaging to understand bacterial membrane vesicle transport
Most bacteria release membrane vesicles to the extracellular environment, which have diverse functions involved in important processes such as horizontal gene transfer, phage decoy and bacterial communications. Also, MVs have immunostimulatory activity which is applied for vaccine development. Despite their various functions, how MVs are formed is not fully understood. The canonical model shows that MVs are formed through the blebbing of the outer membrane in Gram-negative bacteria. We took advantage of live-cell imaging and found a different MV formation route from blebbing where MVs are formed through a process termed explosive cell lysis in Pseudomonas aeruginosa. RNA-seq of MVs revealed that explosive cell lysis is triggered by a peptidoglycan degrading enzyme, endolysin. Endolysin is a widely conserved enzyme that is typically encoded in the prophage region. Further analysis showed the involvement of endolysin in triggering MV formation in Gram-positive bacteria including mycolic acid containing bacteria. Our results demonstrate that MVs are formed through different route that may determine their cargo and therefore their functions. I will introduce how live cell imaging and single cell analysis provided us key findings that may uncover the important steps involved in shuttling MVs.