A convergent proline biosynthetic step couples cell wall integrity to virulence in Cryptococcus neoformans

In Cryptococcus neoformans, Pro3 is a metabolic gatekeeper: pro3Δ shows significantly attenuated virulence in a murine infection model with growth defects and impaired cell wall integrity.

• Why it matters: Amino acid biosynthesis is a key fitness determinant in fungal pathogens, but how proline biosynthesis—especially its convergent steps—supports virulence and cell wall integrity is unclear.
• What they did: The study characterized proline biosynthetic enzymes Pro1, Pro2, and Pro3, mapping two P5C-producing routes and testing proline biosynthetic mutants in vitro and in a murine infection model.
• The result: While pro1Δ and pro2Δ retained full virulence despite proline auxotrophy, pro3Δ’s cell wall defects were not resolved by disrupting P5C-generating routes, suggesting distinct mechanisms for growth versus cell wall homeostasis.