Tec1 mediates the pheromone response of the white phenotype of Candida albicans: insights into the evolution of new signal transduction pathways

PLoS Biol. 2010 May 4;8(5):e1000363. doi: 10.1371/journal.pbio.1000363.

Abstract

The way in which signal transduction pathways evolve remains a mystery, primarily because we have few examples of ones that have newly evolved. There are numerous examples of how signal transduction pathways in the same organism selectively share components, most notably between the signal transduction pathways in Saccharomyces cerevisiae for the mating process, the filamentation process, cell wall integrity, ascospore formation, and osmoregulation. These examples, however, have not provided insights into how such pathways evolve. Here, through construction of an overexpression library for 107 transcription factors, and through mutational analyses, we have identified the transcription factor Tec1 as the last component of the newly evolved signal transduction pathway that regulates the pheromone response of the white cell phenotype in Candida albicans. The elucidation of this last component, Tec1, establishes a comprehensive description of the pheromone response pathway in the white cell phenotype of C. albicans, providing a unique perspective on how new signal transduction pathways may evolve. The three portions of this new regulatory pathway appear to have been derived from three different ancestral programs still functional in C. albicans. The upstream portion, including signals, receptors, the trimeric G protein complex, and the MAP kinase cascade, was derived intact from the upstream portion of the opaque pheromone response pathway of the mating process; Tec1, the transcription factor targeted by the MAP kinase pathway, was derived from a filamentation pathway; and the white-specific downstream target genes were derived from an ancestral biofilm process. The evolution of this pheromone response pathway provides a possible paradigm for how such signal transduction pathways evolve.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Candida albicans* / genetics
  • Candida albicans* / metabolism
  • Candida albicans* / physiology
  • DNA-Binding Proteins* / genetics
  • DNA-Binding Proteins* / metabolism
  • Evolution, Molecular*
  • Fungal Proteins* / genetics
  • Fungal Proteins* / metabolism
  • Gene Expression Regulation, Fungal*
  • MAP Kinase Signaling System / genetics
  • MAP Kinase Signaling System / physiology
  • Molecular Sequence Data
  • Phenotype
  • Pheromones / genetics
  • Pheromones / metabolism*
  • Signal Transduction* / genetics
  • Transcription Factors* / genetics
  • Transcription Factors* / metabolism

Substances

  • DNA-Binding Proteins
  • Fungal Proteins
  • Pheromones
  • TEC1 protein, Candida albicans
  • Transcription Factors