Crosstalk between cAMP and pheromone signalling pathways in Ustilago maydis

Mol Gen Genet. 1998 Nov;260(2-3):193-8. doi: 10.1007/s004380050885.


In the phytopathogenic basidiomycete Ustilago maydis mating and dikaryon formation are controlled by a pheromone/receptor system and the multiallelic b locus. Recently, a gene encoding a G protein alpha subunit, gpa3, was isolated and has subsequently been implicated in pheromone signal transduction. Mutants deleted for gpa3 are sterile and nonpathogenic, and exhibit a morphology that is similar to that of mutants with defects in the adenylate cyclase gene uac1. We have found that the sterility and mutant morphology of gpa3 deletion strains can be rescued by exogenous cAMP. In these mutants and in the corresponding wild-type strains, exogenous cAMP stimulates pheromone gene expression to a level comparable to that seen in the pheromone-stimulated state. In addition, we demonstrate that uac1 is epistatic to gpa3. We conclude that Gpa3 controls the cAMP signalling pathway in U. maydis and discuss how this pathway feeds into the pheromone response.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cyclic AMP / metabolism*
  • Cyclic AMP / pharmacology
  • Fungal Proteins*
  • GTP-Binding Protein alpha Subunits*
  • GTP-Binding Proteins / genetics*
  • GTP-Binding Proteins / metabolism
  • Gene Expression Regulation, Fungal / drug effects
  • Genetic Complementation Test
  • Heterotrimeric GTP-Binding Proteins*
  • Phenotype
  • Pheromones / genetics
  • Pheromones / metabolism*
  • Signal Transduction
  • Ustilago / drug effects
  • Ustilago / genetics
  • Ustilago / metabolism*


  • Fungal Proteins
  • GTP-Binding Protein alpha Subunits
  • Gpa3 protein, Ustilago maydis
  • Pheromones
  • Cyclic AMP
  • GTP-Binding Proteins
  • Heterotrimeric GTP-Binding Proteins