RNASeq of drug-resistant Candida glabrata
Although host stresses are considered a major barrier against the emergence of echinocandin resistance (ECR) in C. albicans, ECR C. glabrata isolates carrying diverse Fks1 and Fks2 mutations are increasingly reported. Nonetheless, impact of equivalent mutations in different FKS alleles and different mutations in a single residue on fitness have not been studied. Moreover, although FKS1 and FKS2 expression is context-dependent, their role during colonization and infection remains uncharacterized. Herein, we employ a diverse array of ex vivo and in vivo models to address those questions. Interestingly, except for Fks2F659del, all tested ECR mutants retained fitness during interaction with THP1 macrophages and neutrophils. Whereas only fks2delta showed fitness defect during interaction with macrophages and neutrophils. Unlike fks2delta, Fks2F659del showed a unique susceptibility to numerous stresses, especially the combination of alterative carbon sources, low pH, and H2O2. Consistent with failure in mounting adaptive oxidative stress response during exposure to H2O2, transcriptomic analysis of intracellular Fks2F659del highlighted dysregulation of oxidative stress response genes, whereas intracellular fks2delta showed hallmarks of metabolic dysregulation. Interestingly, Fks2F659del was outcompeted by wildtype and Fks2F659V during gut colonization and systemic infection. Importantly, whereas both FKS1 and FKS2 were required to establish gut colonization, only FKS2 was required for systemic infection. Therefore, our study highlights that the notable prevalence of ECR C. glabrata is likely driven by retaining their fitness in various niches and ability to overcome host-imposed obstacles may determine their clinical significance. We also show that the essentiality of FKS1 and FKS2 is dictated by niche-specific requirements.