PLoS Pathogens (Nov 2017)

Lipopolysaccharide structure impacts the entry kinetics of bacterial outer membrane vesicles into host cells.

  • Eloise J O'Donoghue,
  • Natalie Sirisaengtaksin,
  • Douglas F Browning,
  • Ewa Bielska,
  • Mohammed Hadis,
  • Francisco Fernandez-Trillo,
  • Luke Alderwick,
  • Sara Jabbari,
  • Anne Marie Krachler

DOI
https://doi.org/10.1371/journal.ppat.1006760
Journal volume & issue
Vol. 13, no. 11
p. e1006760

Abstract

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Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections.