Evolution of the pathogenic mold on high copper levels identifies novel resistance genes.

is the leading cause of severe mold infections in immunocompromised patients. This common fungus possesses innate attributes that allow it to evade the immune system, including its ability to survive the high copper (Cu) levels in phagosomes. Our previous work has revealed that under high Cu levels, the transcription factor AceA is activated, inducing the expression of the copper exporter CrpA to expel excess Cu. To identify additional elements in Cu resistance, we evolved wild-type and mutant Δ or Δ strains under increasing Cu concentrations. Sequencing of the resultant resistant strains identified both shared and unique evolutionary pathways to resistance. Reintroduction of three of the most common mutations in genes encoding Pma1 (plasma membrane H-ATPase), Gcs1 (glutamate cysteine-ligase), and Cpa1 (carbamoyl-phosphate synthetase), alone and in combination, into wild-type confirmed their additive role in conferring Cu resistance. Detailed analysis indicated that the mutation L424I preserves Pma1 H-ATPase activity under high Cu concentrations and that the mutation A37V confers a survival advantage to conidia in the presence of Cu. Interestingly, simultaneous mutations of all three genes did not alter virulence in infected mice. Our work has identified novel Cu-resistance pathways and provides an evolutionary approach for dissecting the molecular basis of adaptation to diverse environmental challenges.IMPORTANCE is the most common mold infecting patients with weakened immunity. Infection is caused by the inhalation of mold spores into the lungs and is often fatal. In healthy individuals, spores are engulfed by lung immune cells and destroyed by a combination of enzymes, oxidants, and high levels of copper. However, the mold can protect itself by pumping out excess copper with specific transporters. Here, we evolved under high copper levels and identified new genetic mutations that help it resist the toxic effects of copper. We studied how these mutations affect the mold's ability to resist copper and how they impact its ability to cause disease. This is the first such study in a pathogenic mold, and it gives us a better understanding of how it manages to bypass our body's defenses during an infection.