FIG 4 .

Growth, conidiation, and cell wall stress tolerance of A. fumigatus pkaC1 mutants. (A and B) Conidia of the indicated strains were point inoculated onto GMM agar plates and incubated for 5 days at 37°C (A) or 40°C (B). T331E, T333A, T333E, T337A, and T337E strains showed marked radial growth defects at both temperatures, while defects were prominent only at 40°C for S175A, S175E, and T331A strains. (C) Quantitation of conidiation following harvest after 120 h of growth on GMM at 37°C. The T331E and T333A substitution mutants showed dramatically reduced conidiation, while all other mutants had wild-type levels or only moderately reduced conidiation. Columns represent averages from three replicates, and error bars represent standard errors. Different letters above columns represent statistically significant differences as determined by Student’s t test (P < 0.05). (D) Sensitivity of WT and ΔpkaC1 mutants to caspofungin (CSP). Conidia (10²) were inoculated into liquid RPMI medium containing indicated concentrations of CSP and incubated at 37°C for 48 h. Loss of PKA in the deletion strain leads to more strongly inhibited growth at 0.25 µg/ml CSP and above, as do the T331E, T333A, and T337E mutations, while the S175A mutation has no visible effect on CSP sensitivity.