Fig. 6: Partner TFs Efg1, Ndt80 and Upc2 affect Ume6 function.

a, For biofilm formation, cells were grown in YPD + 400 µM BPS at 37 °C for 24 h, and biofilms were stained with calcofluor-white. The side-view projection images represent three independent experiments (n = 3). b,c, Ume6 partners Efg1, Ndt80 and Upc2 affect the DNA binding capability of Ume6. Data are presented for hypha-associated genes (b) or biofilm-associated metabolic gene ERG251 (c). ChIP-qPCR was performed using three biological replicates grown in YPD + 400 μM BPS for 4 h at 37 °C (n = 3). ChIP was performed using formaldehyde-fixed cell lysates against anti-HA antibody. Values are the mean ± s.d. of three biological replicates. Statistical significance was determined using two-sided unpaired Student’s t-test. d–f, Bar graphs indicating relative ECE1 (d), HGC1 (e) or ERG251 (f) mRNA levels in indicated strains. Each strain was grown in YPD + 400 µM BPS at 37 °C for 4 h. Total RNAs of three independent biological samples were extracted and used for qPCR determination (n = 3). Values are the mean ± s.d. of three biological replicates. Statistical significance was determined using two-sided unpaired Student’s t-test. g,h, Bar graphs indicating relative RNA levels from ERG genes, ALS3, HGC1, HWP1 (g) and hypoxia-responsive genes (h) in indicated strains. Each strain was grown in YPD at 37 °C for 24 h under biofilm conditions. Total RNA from three independent biological samples was extracted and used for qPCR determination (n = 3). Values are the mean ± s.d. of three biological replicates. Statistical significance was determined using two-sided unpaired Student’s t-test. All strains used in a–h are homozygous for alleles indicated. The genotype of the untagged strain is UME6^+/+. i, Hitchhiker model for Ume6 function. When hypha formation is initiated (left), UME6 expression has just been induced and there is little Ume6 protein in the cell. Expression of newly induced genes is activated by Efg1, Ndt80 and Upc2 bound to their promoter regions. When hyphae reach the elongation stage (right), UME6 has been fully induced. Ume6 reaches target gene promoters by hitchhiking with Efg1, Ndt80 or Upc2. We propose that Ume6 binds to DNA with low affinity, and binding is stabilized by Ume6–Efg1, Ume6–Ndt80 or Ume6–Upc2 complex formation.