tec1 mediates the pheromone response of the white phenotype of candida albicans insights into the evolution of new signal transduction pathwaystec1介导的信息素反应的白色白色念珠菌的表型洞察新的信号转导途径的进化.pdf

Tec1 Mediates the Pheromone Response of the White Phenotype of Candida albicans: Insights into the Evolution of New Signal Transduction Pathways . . Nidhi Sahni , Song Yi , Karla J. Daniels, Guanghua Huang, Thyagarajan Srikantha, David R. Soll* Department of Biology, The University of Iowa, Iowa City, Iowa, United States of America 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 pathw