Figure 1

Regulation of hyphal formation by the HIR complex. (A) hir1Δ/Δ cells are defective in serum-induced hyphal formation on solid medium. Colony morphology was inspected after 3 days. Scale bar corresponds to 1 mm. (B) Loss of HIR1 decreases hyphal formation in liquid medium. Hyphal formation of WT and hir1Δ/Δ cells was evaluated in YPD supplemented with 10% FCS at 37 °C after the indicated time points. (C) Hir1 controls hyphal-specific gene (HSG) expression. ECE1 and RHD1 gene expression was measured after 30 min of hyphal induction via RT-qPCR. Transcript levels were normalized to the expression of the reference gene RIP1 ²². (D) HIR complex mutants display decreased hyphal formation. Colony morphology of hpc2Δ/Δ, hir2Δ/Δ and hir3Δ/Δ was examined as in (A). Scale bar corresponds to 1 mm. (E) Hir1 associates with Hir2 and Hir3 in C. albicans. Hir1 was epitope-tagged with 9myc in either WT background or in strains lacking one HIR complex component and subjected to native immunoprecipitation. Precipitated proteins were separated through a 10% SDS-PAGE gel and visualized by silver staining. Detected protein bands were cut out and identified via mass spectrometry analysis. The indicated molecular weight for Hir3 and Hir2 are derived from mass spectrometry analysis. (F) Hyphal formation is Cac2-independent. Colony morphology of WT cells and cells lacking CAC2 and RTT106 was analyzed as above (A). Scale bar corresponds to 1 mm. (B,C) Data are presented as mean + SD of three independent experiments. For significance testing, hir1Δ/Δ cells were compared to WT cells. n.s. not significant, *P < 0.05, **P < 0.01, ***P < 0.001 with Student’s t-test.