Medicinal genetics approach towards identifying the molecular target of a novel inhibitor of fungal cell wall assembly

Mol Microbiol. 2003 May;48(4):1029-42. doi: 10.1046/j.1365-2958.2003.03481.x.

Abstract

Glycosylphosphatidylinositol (GPI)-anchored cell wall mannoproteins are required for the adhesion of pathogenic fungi, such as Candida albicans, to human epithelium. Small molecular inhibitors of the cell surface presentation of GPI-anchored mannoproteins would be promising candidate drugs to block the establishment of fungal infections. Here, we describe a medicinal genetics approach to identifying the gene encoding a novel target protein that is required for the localization of GPI-anchored cell wall mannoproteins. By means of a yeast cell-based screening procedure, we discovered a compound, 1-[4-butylbenzyl]isoquinoline (BIQ), that inhibits cell wall localization of GPI-anchored mannoproteins in Saccharomyces cerevisiae. Treatment of C. albicans cells with this compound resulted in reduced adherence to a rat intestine epithelial cell monolayer. A previously uncharacterized gene YJL091c, named GWT1, was cloned as a dosage-dependent suppressor of the BIQ-induced phenotypes. GWT1 knock-out cells showed similar phenotypes to BIQ-treated wild-type cells in terms of cell wall structure and transcriptional profiles. Two different mutants resistant to BIQ each contained a single missense mutation in the coding region of the GWT1 gene. These results all suggest that the GWT1 gene product is the primary target of the compound.

MeSH terms

  • Amino Acid Sequence
  • Candida albicans / drug effects*
  • Candida albicans / metabolism
  • Cell Adhesion
  • Cell Wall / drug effects*
  • Cell Wall / metabolism
  • Glycosylphosphatidylinositols / biosynthesis*
  • Glycosylphosphatidylinositols / metabolism
  • Inositol / metabolism
  • Isoquinolines / pharmacology*
  • Molecular Sequence Data
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology
  • Sequence Homology, Amino Acid

Substances

  • 1-(4-butylbenzyl)isoquinoline
  • GWT1 protein, S cerevisiae
  • Glycosylphosphatidylinositols
  • Isoquinolines
  • Saccharomyces cerevisiae Proteins
  • Inositol