Background: To gain further insight into the cellular processes affected by the antifungal drug caspofungin (CAS) we analyzed a unique S. cerevisiae mutant collection made of 4787 individual knockout mutations of non-essential genes, to identify new genes affecting resistance to the drug. Methods: The entire collection of 4787 knockout strain mutants was screened for CAS hypersensitivity (CAS-hs) and resistance (CAS-r). MICs were determined by the NCCLS broth microdilution method using YPD rich medium. Results: Disruption of 93 new genes led to CAS-hs (2-8 fold reduction of MIC). 29/93 are involved in cell wall and cytoskeletal function (e.g FKS1, SBE2, CHS3,5,7, HOC1), 15 in vacuole function (e.g VPS15,25,41,65, VMA4,8, TPO1), and 17 in control of transcription/translation (e.g CCR4, ELP4, SSE1, SSZ1). Disruption of 29 additional genes led to CAS-r (2-4 fold increase of MIC). 8 are involved in cell wall and cytoskeletal function (e.g FKS2, Slg1, Vrp1), 5 in vacuole function (e.g VPS67,74, SAC2), and 5 in control of transcription/translation. Some of the genes identified also enhanced or decreased resistance to amphotericin B (AMB), fluconazole, flucytosine (FC) and calcofluor. Interestingly, 14 of the CAS-r strains were hypersensitive to one or more of the other drugs tested: the VRP1 deleted strain is fourfold more resistant to CAS, but is also fourfold more sensitive to AMB and FC as compared to the wild type strain. Conclusions: Our results provide a global view of CAS resistance, and can be used to identify novel gene targets and pathways whose inactivation may significantly enhance the efficacy of CAS.
Full conference title:
43rd Interscience Conference on Antimicrobial Agents
- ICAAC 43rd