Signal transduction cascades regulating pseudohyphal differentiation of Saccharomyces cerevisiae

In response to nitrogen limitation, diploid cells of the yeast Saccharomyce s cerevisiae undergo a dimorphic transition to filamentous pseudohyphal gro wth. At least two signaling pathways regulate filamentation. One involves c omponents of the MAP kinase cascade that also regulates mating of haploid c ells. The second involves a nutrient-sensing G-protein-coupled receptor tha t signals via an unusual G(alpha) protein, cAMP and protein kinase A. Recen t studies reveal crosstalk between these pathways during pseudohyphal growt h. Related MAP kinase and cAMP pathways regulate filamentation and virulenc e of human and plant fungal pathogens, and represent novel targets for anti fungal drug design.