Mapping virulence-associated protein interaction networks reveals regulators of thermotolerance in Cryptococcus neoformans

The study of protein-protein interactions (PPIs) in the pathogenic fungal species Cryptococcus neoformans has unveiled critical regulators of thermotolerance and virulence. By utilizing size exclusion chromatography coupled with mass spectrometry on the secreted and cellular proteomes of the fungus, researchers identified 216 unique proteins in 24 secretome fractions and 1699 unique proteins in the proteome fractions.

The predicted secretome networks revealed proteins associated with vesicles and virulence, suggesting a role in extracellular defense. The cryptococcal proteome, on the other hand, highlighted interactions among proteins with defined roles in fungal virulence, particularly in protein stability and thermotolerance. Two previously uncharacterized proteins, CNAG_00287 and CNAG_05199, were found to be involved in complex formation with heat-shock proteins (HSP).

Further analysis of the sequence and structure homology suggested that CNAG_00287 is a tetratricopeptide repeat-containing co-chaperone that modulates Hsp 70 activity. CNAG_05199, on the other hand, was proposed to function as a Hsp70. To validate the thermotolerance role of CNAG_00287, researchers found that its absence significantly impaired fungal growth in nutrient-limited media at 37°C.

Overall, this work provides a comprehensive understanding of virulence-associated PPIs within C. neoformans and identifies new molecular regulators of thermotolerance that contribute to fungal pathogenicity.