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Bacterial killing in macrophages and amoeba: do they all use a brass dagger?

Nadezhda German1, Dominik Doyscher, Christopher Rensing

  • 1Research Triangle Institute, Research Triangle Park, NC 27709, USA.

Future Microbiology
|September 25, 2013
PubMed

Insights

Predatory protozoa may use soft metal mechanisms, like macrophages, to kill bacteria. This suggests that protozoan grazing likely selects for copper resistance in environmental bacteria.

Area of Science:

  • Microbiology
  • Immunology
  • Environmental Science

Background:

  • Macrophages utilize 'brass dagger' mechanisms, involving elevated copper and zinc, to destroy pathogens within phagosomes.
  • Bacterial efflux systems counteract toxic metal accumulation, highlighting the significance of metal homeostasis in microbial survival.

Purpose of the Study:

  • To explore the potential for similar soft metal-based bacterial killing mechanisms in predatory protozoa.
  • To investigate the role of metal ions in host-pathogen interactions beyond mammalian immunity.

Main Methods:

  • Comparative analysis of known macrophage-mediated antimicrobial mechanisms.
  • Review of bacterial metal resistance strategies and their potential relevance to protozoan predation.

Main Results:

  • Macrophages employ oxidative burst, metal efflux (Fe(II), Mn(II)), and elevated phagosomal Cu(I)/Zn(II) ('brass dagger') to eliminate bacteria.
  • Bacteria possess sophisticated efflux systems to manage toxic metal concentrations, indicating evolutionary pressure.

Conclusions:

  • Protozoa, like macrophages, may employ soft metal-based strategies to control bacterial populations.
  • Protozoan grazing is a likely environmental factor driving the selection for copper resistance in bacteria.

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