Convergent evolution of peptide-based quorum sensing required for virulence in a eukaryotic pathogen. Cryptococcus neoformans

Bacterial quorum sensing (QS) systems are characterized by the regulated biogenesis and sensing of specialized signaling molecules. Here, we describe a peptide, Qsp1, secreted by the fungal pathogen Cryptococcus neoformans. Mutants lacking Qsp1 are attenuated for infection, pulmonary accumulation, and growth within macrophages. Qsp1 promotes density-dependent cell wall integrity and resistance to extreme environments. Qsp1 is also required for a secreted aspartyl protease activity required for virulence. Further biochemical and large-scale genetic investigations reveal that cleavage of Qsp1 from the C-terminal of a pro-peptide requires a cell-associated serine protease and Qsp1 sensing requires a predicted oligopeptide importer. Strikingly, these features closely mirror the hallmarks of a peptide-based QS system found in gram-positive bacteria, despite no ancestral relationship between individual components. Our studies thus reveal a convergently evolved, peptide-based QS system required for the virulence of a fungal pathogen. Overall design: RNA-Seq or ChIP-Seq to compare multiple Cryptococcus neoformans genotypes using the HiSeq 2500 platform