A yeast two-hybrid assay using SSCMK1 as bait revealed that this kinase interacts with SSHSP90 at the C terminal portion of HSP90. Inhibiting buy LY2109761 HSP90 brought about thermal intolerance in S. schenckii yeast cells and the development of a morphology at 35°C reminiscent of that observed in the SSCMK1 RNAi transformants.

This suggests that the role of SSCMK1 in thermotolerance could be through its effects on SSHSP90. These results confirmed SSCMK1 as an important enzyme involved in the dimorphism of S. schenckii. This study constitutes the first report of the transformation of S. schenckii and the use of RNAi to study gene function in this fungus. Methods Strains S. schenckii (ATCC 58251) was used for all experiments. Stock cultures were maintained in Sabouraud dextrose agar slants at 25°C as described previously [56]. S. cerevisiae strains AH109 and Y187 were used for the yeast two-hybrid screening and were supplied with the MATCHMAKER Two-Hybrid System (Clontech Laboratories Inc., Palo Alto, CA, USA). Culture see more conditions S. schenckii yeast cells were obtained by inoculating BI2536 conidia in 125 ml flask containing 50 ml of a modification of medium M. The cultures were incubated at 35°C with shaking at 100 rpm for 5 days as described previously [56]. Mycelia were obtained by inoculating conidia into a 125 ml flask containing 50 ml of this medium and incubated at 25°C without shaking. Solid cultures

were obtained by inoculating conidia or yeast cells in a modification of medium M plates with added agar (15%) and/or geneticin (300 or 500 μg/ml) and incubated at 25°C or 35°C

according to the experimental design. For the growth determinations in the presence of geldanamycin (GdA, InvivoGen, San Diego, CA, USA), conidia from 10 day-old mycelial slants (109 cells/ml) were resuspended as described previously [56] and inoculated in 125 ml flasks containing 50 ml a modification of medium M with different concentrations of GdA (2, 5 and 10 μM). The cultures were incubated at 35°C with aeration and the growth recorded as OD 600 nm at 3, 5 and 7 days of incubation and compared to that of the controls containing only dimethyl sulfoxide (DMSO, 250 μl/50 ml of medium), the solvent used for resuspending GdA. The results were expressed as the OD at 600 nm of cells growing in the presence MYO10 of geldanamycin/OD 600 nm of the controls ×100 ± one standard deviation of three independent determinations. The statistical significance of the differences observed in the data was analyzed using multiple comparisons with Student’s T test and a Bonferroni correction was applied. An aliquot of the cell suspension of the control cells and cells grown in geldanamycin (10 μM) containing medium were mounted on lactophenol cotton blue and observed microscopically after 7 days of incubation. Microscopy Microscopic observations of the fungus were done using a Nikon Eclipse E600, equipped with a Nikon Digital Sight DS-2Mv and the NIS-Elements F 2.