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Updated: Jun 23, 2026

Size Exclusion Chromatography to Analyze Bacterial Outer Membrane Vesicle Heterogeneity
07:26

Size Exclusion Chromatography to Analyze Bacterial Outer Membrane Vesicle Heterogeneity

Published on: March 31, 2021

Cellular effects of outer membrane vesicles isolated from pks-positive strains of bacteria

Jeremy J Colón-Morales1, Yermary Morales-Lozada2, Bismark Madera2

  • 1University of Puerto Rico, Medical Sciences Campus.

Research Square
|June 22, 2026
PubMed

Insights

Outer membrane vesicles (OMVs) from pks-positive bacteria contribute to colibactin toxicity by damaging host cells. These OMVs enter cells, causing DNA damage and reducing viability, indicating a role in bacterial pathogenesis.

Area of Science:

  • Microbiology
  • Genotoxicology
  • Cell Biology

Background:

  • The pks island in gram-negative bacteria produces genotoxic colibactin, a DNA-damaging compound.
  • The transport mechanism of colibactin into host cells remains largely unknown.
  • Outer membrane vesicles (OMVs) are potential mediators of bacterial toxin delivery.

Purpose of the Study:

  • To investigate the role of OMVs in colibactin-mediated host cell toxicity.
  • To determine if OMVs can deliver colibactin or its precursors to host cells.
  • To characterize the cellular responses to OMVs from pks-positive bacteria.

Main Methods:

  • Exposure of HeLa cells to OMVs from wild-type NC101 (pks+) and a ΔclbP mutant.
  • Assessment of cell viability, nucleus size (megalocytosis), and DNA repair activation.
  • High-resolution confocal microscopy to track OMV internalization and localization.

Main Results:

  • OMVs from both wild-type and mutant strains reduced HeLa cell viability.
  • OMVs induced megalocytosis, with a more pronounced effect when localized within the nucleus.
  • OMVs were internalized by cells and trafficked to the nucleus, activating DNA repair pathways.

Conclusions:

  • OMVs play a significant role in delivering genotoxic compounds like colibactin.
  • OMV-mediated damage to host cells, including DNA damage and reduced viability, mimics phenotypes of pks+ E. coli infections.
  • While OMVs contribute to pks-associated damage, not all observed effects are exclusively pks-specific.
Keywords:
OMVcolibactinmegalocytosisouter-membrane vesiclespks

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