TABLE 2.

Echinocandin susceptibility of S. cerevisiae ScFKS wild-type strains and mutants derived from them

StrainScFKS1 alleleSusceptibility to L-733560
Whole-cell MICa (μg/ml)GS IC50b (μM)
W303-1AWild-type ScFKS10.40.9
Scfks1Δ (pFKS1)Plasmid-encoded ScFKS10.40.4
R560-1CScfks1-21625
Scfks1Δ (pfks1-2)F639I820
X2180-1AWild-type ScFKS10.60.9
MS10Scfks1-3620
Scfks1Δ (pfks1-3)D646Y44
MS14Scfks1-485
Scfks1Δ (pfks1-4)R1357S103
YFK931-7BScfks1-1c0.10.3
YFK978Scfks1-1 Scfks2-1345
Scfks1Δ (pfks2-1)V641K835
  • a Strains were grown in either SD (wild-type and fks1 mutants), SD-leucine (pfks1 transformants) or YPD (fks1-1 mutants). Cells from mid-log phase cultures were diluted to OD600 < 0.01 and used as inocula. Absorbance was read after 24 h at 30°C; the MIC was defined as the lowest drug concentration that reduced optical density to ≤ 10% of growth in drug-free control wells.

  • b Inhibition of crude membrane-associated GS activity was measured as described in Materials and Methods. L-733560 was titrated from 0.02 to 50 μM in the reactions.

  • c Scfks1-1 is a loss-of-function allele (11).