Phr1p, a glycosylphosphatidylinsitol-anchored β(1,3)-glucanosyltransferase critical for hyphal wall formation, localizes to the apical growth sites and septa in Candida albicans

Fungal Genet Biol. 2011 Aug;48(8):793-805. doi: 10.1016/j.fgb.2011.05.003. Epub 2011 May 12.


Cell wall biogenesis is a dynamic process relying on the coordinated activity of several extracellular enzymes. PHR1 is a pH-regulated gene of Candida albicans encoding a glycosylphosphatidylinositol-anchored β(1,3)-glucanosyltransferase of family GH72 which acts as a cell wall remodelling enzyme and is crucial for morphogenesis and virulence. In order to explore the function of Phr1p, we obtained a green fluorescent protein (GFP) fusion to determine its localization. During induction of vegetative growth, Phr1p-GFP was concentrated in the plasma membrane of the growing bud, in the mother-bud neck, and in the septum. Phr1p-GFP was recovered in the detergent-resistant membranes indicating its association with the lipid rafts as the wild type Phr1p. Upon induction of hyphal growth, Phr1p-GFP highly concentrated at the apex of the germ tubes and progressively distributed along the lateral sides of the hyphae. Phr1p-GFP also labelled the hyphal septa, where it colocalized with chitin. Localization to the hyphal septa was perturbed in nocodazole-treated cells, whereas inhibition of actin polymerization hindered the apical localization. Electron Microscopy analysis of the hyphal wall ultrastructure of a PHR1 null mutant showed loss of compactness and irregular organization of the surface layer. These observations indicate that Phr1p plays a crucial role in hyphal wall formation, a highly regulated process on which morphogenesis and virulence rely.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Candida albicans / genetics
  • Candida albicans / growth & development*
  • Candida albicans / metabolism*
  • Candida albicans / ultrastructure
  • Cell Wall / metabolism*
  • Chitin / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Glucan Endo-1,3-beta-D-Glucosidase / genetics
  • Glucan Endo-1,3-beta-D-Glucosidase / metabolism
  • Glycosylphosphatidylinositols / genetics
  • Glycosylphosphatidylinositols / metabolism
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Hyphae / growth & development*
  • Hyphae / metabolism
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Microscopy, Confocal
  • Microscopy, Fluorescence
  • Microscopy, Phase-Contrast
  • Morphogenesis
  • Polymerization


  • Actins
  • Fungal Proteins
  • Glycosylphosphatidylinositols
  • Membrane Glycoproteins
  • PHR1 protein, Candida albicans
  • Chitin
  • Green Fluorescent Proteins
  • 1,3-beta-glucanosyltransferase
  • Glucan Endo-1,3-beta-D-Glucosidase