Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, United States
Ignacio A Zuleta
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States; California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
Kaitlin F Mitchell
Department of Medicine, University of Wisconsin, Madison, United States; Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, United States
David R Andes
Department of Medicine, University of Wisconsin, Madison, United States; Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, United States
Hana El-Samad
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States; California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, United States
Alexander D Johnson
Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, United States; Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, United States
Evolutionary changes in transcription networks are an important source of diversity across species, yet the quantitative consequences of network evolution have rarely been studied. Here we consider the transcriptional ‘rewiring’ of the three GAL genes that encode the enzymes needed for cells to convert galactose to glucose. In Saccharomyces cerevisiae, the transcriptional regulator Gal4 binds and activates these genes. In the human pathogen Candida albicans (which last shared a common ancestor with S. cerevisiae some 300 million years ago), we show that different regulators, Rtg1 and Rtg3, activate the three GAL genes. Using single-cell dynamics and RNA-sequencing, we demonstrate that although the overall logic of regulation is the same in both species—the GAL genes are induced by galactose—there are major differences in both the quantitative response of these genes to galactose and in the position of these genes in the overall transcription network structure of the two species.
