Extracellular glycosylphosphatidylinositol-anchored mannoproteins and proteases of Cryptococcus neoformans.
Extracellular proteins of Cryptococcus neoformans are involved in the pathogenesis of cryptococcosis, and some are immunoreactive antigens that may potentially serve as candidates for vaccine development. To further study the extracellular proteome of the human fungal pathogen Cry. neoformans, we conducted a proteomic analysis of secreted and cell wall-bound proteins with an acapsular strain of Cry. neoformans. Proteins were identified from both intact cells and cell walls. In both cases, extracellular proteins were removed with trypsin or beta-glucanase, and then all proteins/peptides were purified by solid-phase extraction, spin dialysis, and HPLC, and identified by liquid chromatography-mass spectrometry. This study identified 29 extracellular proteins with a predicted N-terminal signal sequence and also a predicted glycosylphosphatidylinositol anchor motif in more than half. Among the novel proteins identified were five glycosylphosphatidylinositol-anchored proteins with extensive Ser/Thr-rich regions but no apparent functional domains, a glycosylphosphatidylinositol-anchored aspartic protease, and a metalloprotease with structural similarity to an elastinolytic metalloprotease of Aspergillus fumigatus. This study suggests that Cry. neoformans has the machinery required to target glycosylphosphatidylinositol-anchored proteins to the cell wall, and it confirms the extracellular proteolytic ability of Cry. neoformans.
Eigenheer
Richard A
RA
Department of Medical Pharmacology and Toxicology Genome and Biomedical Sciences Facility, University of California, California 95616, USA.
Jin Lee
Young
Y
Blumwald
Eduardo
E
Phinney
Brett S
BS
Gelli
Angie
A
D000595:Amino Acid Sequence; D002473:Cell Wall / Q000737:chemistry; D003455:Cryptococcus neoformans / Q000737:chemistry* / Q000201:enzymology*; D005656:Fungal Proteins / Q000032:analysis* / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010447:Peptide Hydrolases / Q000032:analysis* / Q000378:metabolism
D005656:Fungal Proteins; D017261:Glycosylphosphatidylinositols; D010447:Peptide Hydrolases