Proteome analysis of Aspergillus fumigatus identifies glycosylphosphatidylinositol-anchored proteins associated to the cell wall biosynthesis

Previous studies in Aspergillus fumigatus (Mouyna I., Fontaine T, Vai M., M onod M., Fonzi W. A., Diaquin M., Popolo L., Hartland R. P., Latge J.-P, J. Biol. Chem. 2000, 275, 14882-14889) have shown that a glucanosyltransferas e playing an important role in fungal cell wall biosynthesis is glycosylpho sphatidylinositol (GPI) anchored to the membrane. To identify other GPI-anc hored proteins putatively involved in cell wall biogenesis, a proteomic ana lysis has been undertaken in A. fumigatus and the protein data were matched with the yeast genomic data. GPI-anchored proteins of A. fumigatus were re leased from membrane preparation by an endogenous GPI-phospholipase C, puri fied by liquid chromatography and separated by two-dimensional electrophore sis. They were characterized by their peptide mass fingerprint through matr ix-assisted laser desorption/ionization-time of flight-(MALDI-TOF)-mass spe ctrometry and by internal amino acid sequencing. Nine GPI-anchored proteins were identified in A. fumigatus. Five of them were homologs of putatively GPI-anchored yeast proteins (Csa1p, Crh1p, Crh2p, Ecm33p, Gas1p) of unknown function but shown by gene disruption analysis to play a role in cell wall morphogenesis. In addition, a comparative study performed with chitin synt hase and glucanosyl transferase mutants of A, fumigatus showed that a modif ication of the growth phenotype seen in these mutants was associated to an alteration of the pattern of GPI-anchored proteins. These results suggest t hat GPI-anchored proteins identified in this study are involved in A. fumig atus cell wall organization.