The cell wall architecture of Candida albicans wild-type cells and cell wall-defective mutants.
In Candida albicans wild-type cells, the beta1, 6-glucanase-extractable glycosylphosphatidylinositol (GPI)-dependent cell wall proteins (CWPs) account for about 88% of all covalently linked CWPs. Approximately 90% of these GPI-CWPs, including Als1p and Als3p, are attached via beta1,6-glucan to beta1,3-glucan. The remaining GPI-CWPs are linked through beta1,6-glucan to chitin. The beta1,6-glucanase-resistant protein fraction is small and consists of Pir-related CWPs, which are attached to beta1,3-glucan through an alkali-labile linkage. Immunogold labelling and Western analysis, using an antiserum directed against Saccharomyces cerevisiae Pir2p/Hsp150, point to the localization of at least two differentially expressed Pir2 homologues in the cell wall of C. albicans. In mnn9Delta and pmt1Delta mutant strains, which are defective in N- and O-glycosylation of proteins respectively, we observed enhanced chitin levels together with an increased coupling of GPI-CWPs through beta1,6-glucan to chitin. In these cells, the level of Pir-CWPs was slightly upregulated. A slightly increased incorporation of Pir proteins was also observed in a beta1, 6-glucan-deficient hemizygous kre6Delta mutant. Taken together, these observations show that C. albicans follows the same basic rules as S. cerevisiae in constructing a cell wall and indicate that a cell wall salvage mechanism is activated when Candida cells are confronted with cell wall weakening.
Kapteyn
J C
JC
Swammerdam Institute of Life Sciences, University of Amsterdam, Kruislaan 318, 1098 SM Amsterdam, The Netherlands. kapteyn@bio.uva.nl
Hoyer
L L
LL
Hecht
J E
JE
Müller
W H
WH
Andel
A
A
Verkleij
A J
AJ
Makarow
M
M
Van Den Ende
H
H
Klis
F M
FM
D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D002176:Candida albicans / Q000166:cytology* / Q000187:drug effects / Q000235:genetics*; D002473:Cell Wall / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002686:Chitin / Q000737:chemistry / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005936:Glucans / Q000737:chemistry / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans
C093538:ALS1 protein, Candida albicans; C113620:ALS3 protein, Candida albicans; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D005656:Fungal Proteins; D005936:Glucans; D017261:Glycosylphosphatidylinositols; C081933:KRE6 protein, S cerevisiae; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans; D002686:Chitin; C064197:beta-1,6-glucan; C011952:nikkomycin