Fig 3. Mutation of the Vip1p kinase domain results in exaggerated pseudohyphal growth.

(A) Diagram indicating phosphatases affecting inositol pyrophosphates. Vip1p phosphatase activity acts redundantly with Ddp1p. (B) Haploid invasive growth phenotypes are shown for strains containing a kinase-defective vip1 allele (D487A) and phosphatase-defective vip1 allele (H548A), respectively. For comparison, haploid wild type and vip1Δ mutants are included. Assays were performed and quantified as described previously. Mean values with standard deviation for three replicates are provided. Scale bar, 2 mm. (C) Surface pseudohyphal filamentation is shown for the indicated homozygous diploid strains grown on low-nitrogen SLAD medium. Mean values with standard deviation for three replicates are provided. Scale bar, 500 μm. (D) Representative InsP profiles of kinase-defective and phosphatase-defective vip1 mutants grown in low-nitrogen minimal media for eight hours. Diploid wild type and vip1Δ/Δ strains grown under identical conditions are shown for comparison. Plots of InsP₇ isoforms and InsP₈ are enlarged in the boxed inset.