Related Experiment Video

Updated: Mar 20, 2026

Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii
10:24

Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii

Published on: April 10, 2020

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Periplasmic crowding and peptidoglycan hydrolase activity as drivers of outer membrane vesiculation in Acinetobacter

Bitnara Kim1, Yongjun Son1, Reagan Lee1

  • 1Laboratory of Molecular Environmental Microbiology, Department of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea.

Communications Biology
|March 19, 2026
PubMed

Insights

Acinetobacter baumannii uses outer membrane vesicles (OMVs) to manage envelope stress. Peptidoglycan hydrolysis, driven by MltB, is crucial for OMV biogenesis during periplasmic crowding stress.

Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • Acinetobacter baumannii generates outer membrane vesicles (OMVs) to mitigate envelope stress.
  • The precise mechanisms governing OMV production under stress conditions are not fully understood.

Purpose of the Study:

  • To investigate the role of periplasmic crowding stress and cell wall remodeling in OMV biogenesis.
  • To elucidate the molecular mechanisms linking envelope stress to OMV formation in Acinetobacter baumannii.

Main Methods:

  • Induction of periplasmic misfolded proteins and stress using a degP mutant at elevated temperatures.
  • Utilizing fluorescence recovery after photobleaching to monitor OMV production.
  • Employing OMV proteomics, western blotting, lipophilic dye quantification, and electron microscopy.

Main Results:

  • Periplasmic crowding stress significantly increases OMV production and vesicle size in degP mutants.
  • OMVs from stressed cells show enrichment of OmpA and LPS.
  • Deletion of mltB eliminates OMV formation in the degP mutant, while its overexpression enhances OMV protrusions in surA mutants.

Conclusions:

  • Peptidoglycan hydrolysis, mediated by MltB, is a critical determinant of OMV biogenesis under periplasmic crowding stress.
  • Cell wall remodeling is intrinsically linked to stress-induced vesicle formation in Acinetobacter baumannii.

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