Figure 1.

C. albicans Hog1 is phosphorylated in response to diverse stresses and Δhog1 cells are sensitive to these stresses. (A) Western blot analysis of Ni²⁺-NTA agarose-purified Hog1-His₆-myc isolated from C. albicans cells after treatment with the following compounds: 5 mM H₂O₂, 0.3 mM menadione, 0.6 M KCl, 1.2 M sorbitol, 10 mM caffeine, 0.5 mM CdSO₄, 2 mM Na₂As₃, 2.0 μM staurosporine, 0.1 mM farnesol, or 20% serum. Western blots were probed with an anti-phospho p38 antibody, which only recognizes the phosphorylated, active form of C. albicans Hog1 (Hog1-P). Total levels of Hog1 protein was determined by stripping and reprobing the blot with an anti-myc antibody that recognizes both phosphorylated and unphosphorylated forms of Hog1 (Hog1). (B) Approximately 10³ cells from exponentially growing wild-type (WT), Δhog1 (JC50), or Δhog1+HOG1 (JC52) strains were spotted onto YPD plates containing the compounds listed above, with the exception that t-BOOH (1 mM) was used instead of H₂O₂. Plates were incubated at 30°C (or 42°C) for 24 h.