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Chlamydia pneumoniae inclusion membrane protein Cpn0585 interacts with multiple Rab GTPases

Claudio Cortes1, Kimberly A Rzomp, Amy Tvinnereim

  • 1Department of Microbiology and Immunology, University of Texas Health Center, Tyler, TX 75708, USA.

Infection and Immunity
|October 3, 2007
PubMed

Insights

Chlamydia pneumoniae uses the inclusion membrane protein Cpn0585 to recruit host Rab GTPases, particularly Rab11. Interfering with this interaction hinders bacterial inclusion development, impacting chlamydial replication.

Area of Science:

  • Microbiology
  • Cell Biology
  • Molecular Biology

Background:

  • Chlamydiae are obligate intracellular bacteria that reside within a host-derived vacuole, the inclusion.
  • Successful chlamydial replication depends on manipulating host cell processes, including membrane trafficking pathways.
  • Rab GTPases are known regulators of membrane trafficking and have been observed to associate with chlamydial inclusions.

Purpose of the Study:

  • To investigate the interaction between Chlamydia pneumoniae inclusion membrane protein Cpn0585 and host Rab GTPases.
  • To determine the role of Cpn0585 in recruiting Rab GTPases to the bacterial inclusion membrane.
  • To assess the impact of Cpn0585-Rab GTPase interactions on chlamydial inclusion development.

Main Methods:

  • Yeast two-hybrid assays to identify interacting Rab GTPases.
  • Glutathione S-transferase pull-down assays to confirm direct and GTP-dependent interactions.
  • Fluorescence microscopy in infected HEp-2 cells to assess colocalization of Cpn0585 with EGFP-tagged Rab GTPases.
  • Antibody staining to determine the orientation of Cpn0585 within the inclusion membrane.
  • Ectopic expression of Cpn0585 to evaluate its effect on chlamydial inclusion development.

Main Results:

  • Cpn0585 directly interacts with Rab1, Rab10, and Rab11 in a GTP-dependent manner.
  • Cpn0585 extensively colocalizes with Rab11A and its constitutively active mutant (Rab11AQ70L) on the inclusion membrane, even early in infection.
  • The Rab GTPase-interacting domain of Cpn0585 is exposed to the host cell cytosol.
  • Ectopic expression of Cpn0585 inhibits C. pneumoniae inclusion development, an effect partially rescued by co-expression of Rab11AQ70L.

Conclusions:

  • Cpn0585 plays a crucial role in recruiting specific Rab GTPases, particularly Rab11, to the Chlamydia pneumoniae inclusion membrane.
  • This recruitment is essential for establishing a suitable niche for chlamydial replication.
  • Disruption of Cpn0585's interaction with Rab GTPases negatively impacts chlamydial fitness and inclusion development.

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