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The novel coccidian micronemal protein MIC11 undergoes proteolytic maturation by sequential cleavage to remove an

Jill M Harper1, Xing W Zhou, Viviana Pszenny

  • 1W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA.

International Journal for Parasitology
|August 18, 2004
PubMed

Insights

Researchers identified a novel protein, TgMIC11, crucial for Toxoplasma gondii invasion. This microneme protein undergoes unique processing and secretion, offering new insights into parasite pathogenesis and control strategies.

Area of Science:

  • Parasitology
  • Cell Biology
  • Molecular Biology

Background:

  • Host cell invasion is essential for the intracellular parasite Toxoplasma gondii's life cycle.
  • Microneme proteins (MICs) are secreted from apical organelles and mediate parasite attachment and invasion.
  • Some MICs lack adhesive motifs, suggesting diverse functions beyond adhesion.

Purpose of the Study:

  • To identify and characterize novel microneme proteins involved in Toxoplasma gondii invasion.
  • To investigate the structure, processing, and localization of the newly identified TgMIC11 protein.

Main Methods:

  • Protein identification and characterization.
  • Analysis of protein trafficking and modification through the secretory system.
  • Dual staining immunofluorescence to confirm protein localization.
  • Investigation of secretion mechanism (calcium dependence).

Main Results:

  • A novel 16 kDa microneme protein, TgMIC11, conserved in coccidian parasites, was identified.
  • TgMIC11 undergoes proteolytic processing to remove an internal propeptide, forming a mature alpha- and beta-chain structure linked by a disulfide bond.
  • TgMIC11 localizes to apical micronemes and is secreted in a calcium-dependent manner.
  • This represents the first characterized Apicomplexa microneme protein with internal propeptide removal.

Conclusions:

  • TgMIC11 is a unique microneme protein with a novel maturation process.
  • Its secretion mechanism and apical localization highlight its role in parasite invasion.
  • Understanding TgMIC11's function may reveal new therapeutic targets for toxoplasmosis.

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