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Actin-based mechanism of holospora obtusa trafficking in Paramecium caudatum

Elena V Sabaneyeva1, M E Derkacheva, K A Benken

  • 1Department of Cytology and Histology, St.-Petersburg State University, 199034 St.-Petersburg, Russia.

Protist
|February 24, 2009
PubMed

Insights

Holospora obtusa bacteria hijack the host cell's actin cytoskeleton for nuclear infection. This process involves bacterial escape from phagosomes and cytoplasmic trafficking, similar to Listeria infections.

Area of Science:

  • Microbiology
  • Cell Biology
  • Parasitology

Background:

  • Holospora obtusa is an obligate endonuclear pathogen of the ciliate Paramecium caudatum.
  • H. obtusa is engulfed via phagocytosis but escapes the phagosome to reach the host macronucleus.
  • A comet-like actin tail trails H. obtusa in the host cytoplasm, similar to Listeria.

Purpose of the Study:

  • To investigate the role of host cell actin and Arp3 in Holospora infection.
  • To elucidate the mechanisms of H. obtusa entry and nuclear trafficking within Paramecium.

Main Methods:

  • Treatment with Cytochalasin D to inhibit actin polymerization.
  • Immunocytochemistry to visualize actin and Arp3.
  • Experimental infection of GFP-actin-transfected Paramecium.

Main Results:

  • Cytochalasin D treatment significantly reduced nuclear infection rates.
  • Paramecium actin1-1 is involved in bacterial escape from phagosomes, cytoplasmic transport, and nuclear entry.
  • Rapid actin filament dynamics in P. caudatum resulted in the loss of actin trails from H. obtusa.
  • Arp3 was detected in the actin trails associated with H. obtusa.

Conclusions:

  • Host cell actin and Arp3 play critical roles in Holospora obtusa infection of Paramecium caudatum.
  • The infection mechanism shares similarities with those of Listeria and Rickettsia, involving actin-based motility.
  • Understanding these host-pathogen interactions provides insights into intracellular bacterial pathogenesis.

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