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Separation of the Cell Envelope for Gram-negative Bacteria into Inner and Outer Membrane Fractions with Technical Adjustments for Acinetobacter baumannii
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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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How the Membrane Attack Complex Damages the Bacterial Cell Envelope and Kills Gram-Negative Bacteria

Dennis J Doorduijn1, Suzan H M Rooijakkers1, Dani A C Heesterbeek1

  • 1Medical Microbiology, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.

Bioessays : News and Reviews in Molecular, Cellular and Developmental Biology
|August 28, 2019
PubMed

Insights

The human immune system uses membrane attack complexes (MACs) to kill bacteria. This review explains how MACs form pores to rupture Gram-negative bacteria, aiding infection treatment.

Area of Science:

  • Immunology
  • Microbiology
  • Structural Biology

Background:

  • The human immune system utilizes membrane attack complexes (MACs) to lyse microorganisms and aberrant cells by forming pores in cell membranes.
  • Recent cryoelectron microscopy studies revealed MACs as asymmetric, flexible pores, explaining their mechanism for rupturing single lipid membranes.

Purpose of the Study:

  • To review recent insights into MAC assembly and pore formation in Gram-negative bacteria.
  • To discuss the mechanisms by which MAC pores kill Gram-negative bacteria, focusing on outer and inner membrane damage.
  • To elaborate on the poorly understood process of MAC-dependent outer membrane damage leading to inner membrane destabilization.

Main Methods:

  • Review of recent functional studies on Gram-negative bacteria.
  • Analysis of single-particle cryoelectron microscopy data on MAC structure.
  • Synthesis of current knowledge on MAC assembly and bacterial membrane interactions.

Main Results:

  • Local assembly of MAC pores by surface-bound C5 convertase enzymes is crucial for stable insertion into the bacterial outer membrane (OM).
  • MAC pores efficiently damage the bacterial inner membrane (IM) after OM insertion, leading to bacterial killing.
  • The precise mechanisms linking MAC-dependent OM damage to IM destabilization require further elucidation.

Conclusions:

  • Understanding MAC assembly and pore formation is key to comprehending Gram-negative bacterial killing.
  • Further research into MAC-mediated membrane damage could lead to novel therapeutic strategies against Gram-negative infections.
Keywords:
C5 convertasesGram-negative bacteriacomplementmembrane attack complexesserum bactericidal activities

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