Oral Presentation Australasia Extracellular Vesicles Conference 2017

Bacterial membrane vesicles transport their DNA cargo to the nucleus of host cells. (#30)

Natalie J Bitto 1 , Ross Chapman 1 , Sacha Pidot 2 , Adam Costin 3 , Camden Lo 3 , Jasmine Choi 1 , Tanya D'Cruze 4 , Eric C Reynolds 4 , Stuart G Dashper 4 , Lynne Turnbull 5 , Cynthia Whitchurch 5 , Tim P Stinear 2 , Katryn J Stacey 6 , Richard L Ferrero 1
  1. Hudson Institute of Medical Research, Melbourne, VIC, Australia
  2. Department of Microbiology and Immunology, The University of Melbourne, Melbourne
  3. Monash Micro Imaging, Monash University, Melbourne
  4. Melbourne Dental School, Bio21 Institute, The University of Melbourne, Melbourne
  5. The ithree institute, University of Technology Sydney, Sydney
  6. School of Chemistry and Molecular Biosciences , University of Queensland, Brisbane

Membrane vesicle (MV) formation is an evolutionarily conserved trait amongst members of all three domains of living organisms. MVs contain a diverse array of biologically active compounds and play a key role in cell-to-cell communication. The MVs released by bacteria contain biologically active products, such as proteins, cell wall components and toxins1. Bacteria use MVs as a means of delivering such factors into eukaryotic host cells, resulting in various biological responses in these cells 2,3. Bacterial MVs have been reported to carry DNA, however, very little is known about the nature of the DNA, nor about its potential actions on host cells. In the present work, we used a PicoGreen-based assay to quantify MV-associated DNA in a range of pathogenic bacteria. This DNA was predominantly found on the external surfaces of the MVs, with smaller amounts located internally. Using the Click-iT EdU assay, we labeled nascent DNA in live bacteria and demonstrated that this DNA could be detected in MVs released from the bacteria during exponential phase growth. From “next generation sequencing”, we demonstrated that MV-associated DNA is chromosomal in origin. Furthermore, thirty-five genes were found to be specifically enriched in the internally located DNA fractions, suggesting a biased packaging of DNA in bacterial MVs. These genes encode factors involved in bacterial virulence, stress response, antibiotic resistance and metabolism. Finally, we showed that MVs are able to transport their bacterial DNA into the cytoplasm of human epithelial cells and to direct this cargo to the nucleus of cells. These findings have important implications regarding the role of MVs in the transfer of genetic material between pathogenic bacteria and host cells, as well as for the use of bacterial MVs in vaccines or therapies.

  1. 1 Kaparakis-Liaskos & Ferrero (2015) Nat. Rev. Immunol. 15: 376-387.
  2. 2 Kaparakis et al. (2010) Cell Microbiol. 12, 372-385.
  3. 3 Irving et al. (2014) Cell Host Microb.15, 623-35.