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Phosphoproteome of Cryptococcus neoformans
Lakshmi Dhevi N Selvan1, Santosh Renuse1, Jyothi Embekkat Kaviyil2
1Institute of Bioinformatics, International Technology Park, Bangalore 560 066, India; Amrita School of Biotechnology, Amrita University, Kollam 690 525, India.
Abstract:
Cryptococcus neoformans is an encapsulated pathogenic yeast, which causes life threatening meningitis in immunocompromised individuals. C. neoformans var. grubii is the most prevalent and virulent form among the two varieties of C. neoformans - C. neoformans var. grubii and C. neoformans var. neoformans. The virulence of C. neoformans is mainly conferred by its capsule and melanin. cAMP dependent PKA-induced phosphorylation events are reported to be associated with the expression of these virulence traits, which highlights the importance of phosphoproteins in virulence and infection. Therefore, we performed global profiling of phosphoproteome of C. neoformans to enable a better understanding of molecular regulation of its virulence and pathogenesis. High resolution mass spectrometry of TiO2 enriched phosphopeptides from C. neoformans var. grubii grown in culture led to the identification of 1089 phosphopeptides derived from 648 proteins including about 45 kinases. Motif enrichment analysis revealed that most CDK family substrates were found to be phosphorylated. This indicates that cyclin-dependent kinases were among the active kinases in the pathogen in culture. These studies provide a framework for understanding virulence mechanisms in the context of signalling pathways in pathogenic yeast. This article is part of a Special Issue entitled: Trends in Microbial Proteomics.
Biological Significance:
C. neoformans is a pathogenic yeast responsible for cryptococcal meningitis. Melanin and polysaccharide capsule have been established as some of the key virulence factors that play a major role in the pathogenesis of C. neoformans. Recent studies have shown the role of kinase mediated signalling pathways in governing biosynthesis of these virulence factors. This study revealed 1540 phosphorylation sites in 648 proteins providing a comprehensive view of phosphoproteins in C. neoformans. This should serve as a useful resource to explore activated signalling pathways in C. neoformans and their association with its virulence and pathogenesis.
Insights
This study profiled phosphoproteins in Cryptococcus neoformans, identifying key phosphorylation sites and kinases involved in virulence. Understanding these phosphoproteins offers insights into the molecular mechanisms of cryptococcal meningitis pathogenesis.
Area of Science:
- Mycology
- Proteomics
- Molecular Biology
Background:
- Cryptococcus neoformans is an encapsulated yeast causing life-threatening meningitis, particularly in immunocompromised individuals.
- The yeast's capsule and melanin are critical virulence factors, with their expression linked to cAMP-dependent protein kinase A (PKA)-induced phosphorylation.
- Phosphoproteins are crucial for understanding the molecular regulation of C. neoformans virulence and infection.
Purpose of the Study:
- To perform a global phosphoproteome profiling of C. neoformans var. grubii.
- To identify key phosphoproteins and active kinases involved in the regulation of virulence traits.
- To provide a framework for understanding virulence mechanisms within signaling pathways.
Main Methods:
- Global phosphoproteome profiling of C. neoformans var. grubii.
- High-resolution mass spectrometry of TiO2-enriched phosphopeptides.
- Motif enrichment analysis to identify kinase substrates.
Main Results:
- Identification of 1089 phosphopeptides from 648 proteins, including approximately 45 kinases.
- Motif enrichment analysis indicated that cyclin-dependent kinase (CDK) family substrates were predominantly phosphorylated.
- This suggests active roles for CDKs in C. neoformans during in vitro culture.
Conclusions:
- The study identified 1540 phosphorylation sites across 648 proteins, offering a comprehensive view of the phosphoproteome.
- Kinase-mediated signaling pathways are implicated in the biosynthesis of C. neoformans virulence factors like melanin and capsule.
- This resource aids in exploring activated signaling pathways and their association with C. neoformans virulence and pathogenesis.
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