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Functional interaction between type III-secreted protein IncA of Chlamydophila psittaci and human G3BP1

Nicole Borth1, Katrin Litsche, Claudia Franke

  • 1Department of Cell and Molecular Biology, Leibniz Institute for Natural Product Research and Infection Biology, Hans Knoell Institute, Jena, Germany.

Plos One
|February 10, 2011
PubMed

Insights

Chlamydophila psittaci uses its Type III secretion system protein IncA to interact with host protein G3BP1. This interaction lowers c-Myc levels, potentially helping the bacteria evade apoptosis and control host cell proliferation.

Area of Science:

  • Microbiology
  • Cell Biology
  • Zoonotic Diseases

Background:

  • Chlamydophila psittaci is a significant zoonotic pathogen causing psittacosis.
  • Chlamydiae are obligate intracellular bacteria with a biphasic developmental cycle within host cells.
  • Type III secretion systems deliver bacterial effector proteins into host cells to manipulate cellular processes.

Purpose of the Study:

  • To investigate the interaction between Chlamydophila psittaci Type III secreted protein IncA and host factors.
  • To elucidate the role of IncA-host protein interactions in Chlamydophila psittaci infection.

Main Methods:

  • Yeast two-hybrid system to identify interacting partners of IncA.
  • GST-pull down and co-immunoprecipitation assays for in vitro and in vivo interaction validation.
  • Fluorescence microscopy to determine protein localization in infected cells.
  • Western blotting to assess host protein levels (c-Myc) after infection or IncA overexpression.

Main Results:

  • Chlamydophila psittaci IncA directly interacts with host protein G3BP1.
  • G3BP1 localizes near the Chlamydophila psittaci inclusion membrane in infected cells.
  • Cp. psittaci infection and IncA overexpression reduce host cell c-Myc protein concentration.
  • The IncA-G3BP1 interaction is crucial for the observed decrease in c-Myc levels.

Conclusions:

  • The interaction between IncA and G3BP1 is a key mechanism employed by Chlamydophila psittaci during infection.
  • Chlamydophila psittaci likely manipulates host c-Myc levels via IncA-G3BP1 interaction to promote bacterial survival.
  • This interaction may contribute to evading host apoptosis and regulating host cell proliferation for pathogen propagation.

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