Identification of major proteins secreted byCryptococcus neoformans

Abstract

The characterization of proteins secreted by Cryptococcus neoformans is of relevance to the identification of vaccine candidates, because concentrated supernatants from the fungus have been shown to be immunoprotective in previous studies. After fractionation of supernatants by anion exchange chromatography and preparative electrophoresis, we obtained the N-terminal amino acid sequences of 13 major proteins. Using a C. neoformans nucleotide database, we were able to clone and sequence the ORFs coding for 12 of these proteins. Some of the genes are identical to previously described ones, while six encode novel proteins, including four putative mannoproteins. The molecular characterization of these and other secreted products may provide useful information in the development of immune-based strategies to control cryptococcosis.

Immunoproteomics and Immunoinformatics Analysis of Cryptococcus Gattii : Novel Candidate Antigens for Diagnosis

“…Such proteins have previously been identified as being essential for intracellular survival, virulence and resistance to oxidative and nitrosative stress in C. neoformans, as reported by Missall et al [63][64][65] and Wang et al [66]. The finding presented here that thiol peroxidase is an antigenic target in C. gattii genotype VGII corroborates the findings of Jobbins et al [56] and supports the hypothesis that this protein is involved in the pathogenesis of C. gattii genotype VGII infection in humans [62,[67][68][69].…”

Identification of Aph1, a Phosphate-Regulated, Secreted, and Vacuolar Acid Phosphatase in Cryptococcus neoformans

“…To date there have been only three published reports, all using acapsular C. neoformans serotype D mutant strains, for which proteomic analysis was utilized to identify the composition of the C. neoformans secretome: Eigenheer et al (29) and Biondo et al (30) identified 29 and 12 extracellular proteins, respectively, while Rodrigues et al (23) identified 76 proteins that were specifically associated with exosome-like vesicles. We performed a proteomic analysis on secretions obtained from the more-virulent encapsulated serotype A strain of C. neoformans , H99, and identified CNAG_02944 (designated Aph1) as the acid phosphatase responsible for the extracellular acid phosphatase activity previously observed by others (7, 15).…”

Unraveling the Novel Structure and Biosynthetic Pathway of O-Linked Glycans in the Golgi Apparatus of the Human Pathogenic Yeast Cryptococcus neoformans

“…Cell-bound or secreted cryptococcal mannoproteins have been reported to be associated with C. neoformans pathogenicity (24) and are involved in the stimulation of host T-cell responses (25,26). C. neoformans has been predicted to contain more than 50 putative mannoproteins, which typically contain potential N-glycosylation sites, putative Ser/Thr-rich regions for O-glycosylation, and a glycosylphosphatidylinositol anchor (26,27). However, the structure and biosynthetic pathway of cryptococcal oligosaccharides assembled on mannoproteins have only been partially characterized.…”