Vesicular Transport in Histoplasma Capsulatum: An Effective Mechanism for Trans-Cell Wall Transfer of Proteins and Lipids in Ascomycetes

Cell Microbiol. 2008 Aug;10(8):1695-710. doi: 10.1111/j.1462-5822.2008.01160.x. Epub 2008 Apr 17.

Abstract

Vesicular secretion of macromolecules has recently been described in the basidiomycete Cryptococcus neoformans, raising the question as to whether ascomycetes similarly utilize vesicles for transport. In the present study, we examine whether the clinically important ascomycete Histoplasma capsulatum produce vesicles and utilized these structures to secrete macromolecules. Transmission electron microscopy (TEM) shows transcellular secretion of vesicles by yeast cells. Proteomic and lipidomic analyses of vesicles isolated from culture supernatants reveal a rich collection of macromolecules involved in diverse processes, including metabolism, cell recycling, signalling and virulence. The results demonstrate that H. capsulatum can utilize a trans-cell wall vesicular transport secretory mechanism to promote virulence. Additionally, TEM of supernatants collected from Candida albicans, Candida parapsilosis, Sporothrix schenckii and Saccharomyces cerevisiae documents that vesicles are similarly produced by additional ascomycetes. The vesicles from H. capsulatum react with immune serum from patients with histoplasmosis, providing an association of the vesicular products with pathogenesis. The findings support the proposal that vesicular secretion is a general mechanism in fungi for the transport of macromolecules related to virulence and that this process could be a target for novel therapeutics.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport / genetics
  • Cell Wall / metabolism*
  • Fungal Proteins / metabolism*
  • Histoplasma / chemistry
  • Histoplasma / metabolism*
  • Histoplasma / ultrastructure*
  • Histoplasmosis / immunology
  • Histoplasmosis / microbiology
  • Host-Pathogen Interactions
  • Lipid Metabolism*
  • Microscopy, Electron, Transmission
  • Phospholipids / analysis
  • Phospholipids / metabolism
  • Secretory Vesicles / chemistry*
  • Secretory Vesicles / metabolism

Substances

  • Fungal Proteins
  • Phospholipids