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Chlamydial TARP is a bacterial nucleator of actin

Travis J Jewett1, Elizabeth R Fischer, David J Mead

  • 1Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.

Proceedings of the National Academy of Sciences of the United States of America
|October 10, 2006
PubMed

Insights

Chlamydia trachomatis uses the translocated actin-recruiting phosphoprotein (TARP) to manipulate host cell actin. TARP directly binds actin, promoting its nucleation and facilitating bacterial entry.

Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • Chlamydia trachomatis entry into host cells involves host actin cytoskeleton remodeling.
  • A type III secreted effector, translocated actin-recruiting phosphoprotein (TARP), is implicated in actin recruitment during internalization.

Purpose of the Study:

  • To elucidate the role of TARP in actin recruitment during Chlamydia trachomatis entry.
  • To identify host cell proteins that associate with TARP.

Main Methods:

  • Used recombinant GST-TARP fusions to identify interacting host proteins.
  • Performed in vitro actin polymerization assays.
  • Conducted domain analysis of TARP.

Main Results:

  • TARP directly associated with actin, promoting actin nucleation.
  • Identified an actin-binding domain in TARP similar to WH2 domain proteins.
  • A proline-rich domain in TARP promoted oligomerization and was essential for TARP-dependent actin nucleation.

Conclusions:

  • TARP directly recruits and nucleates actin filaments.
  • TARP utilizes WH2-like and proline-rich domains to mediate actin cytoskeleton manipulation.
  • This mechanism explains how Chlamydia trachomatis induces localized cytoskeletal changes for host cell entry.

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