Modulators of MAPK pathway activity during filamentous growth in Saccharomyces cerevisiae .

Signaling pathways control the response to stimuli. In yeast, a signaling (MAPK) pathway controls a fungal behavioral response called filamentous growth. A genetic screen was performed to identify spontaneous mutants that show hyperactivity of a MAPK pathway-dependent reporter. Select mutants were analyzed by whole-genome sequencing. New alleles in known regulatory proteins were identified. A potential inhibitory domain in the C-terminus of the transcription factor Ste12p was also uncovered. Our results indicate that filamentous growth is determined by the combinatorial effects of multiple positive and negative regulatory inputs.