Alexander D. Johnson

1. Molecular Biology of Transcription Circuit Evolution. The gradual rewiring of transcriptional circuits over evolutionary timescales is a major source of the diversity of life. We study the molecular mechanisms that underlie these rewiring events and how these changes in circuitry lead to differences among species. We carry out this work in a large group of unicellular eukaryotes (the fungi) including the "model" eukaryote Saccharomyces cerevisiae and the human fungal pathogen Candida albicans. 2. Candida albicans pathogenesis. C. albicans is a species of fungus that typically resides asymptomatically in the gastrointestinal tracts of humans and other warm-blooded animals. It is also the most prevalent human fungal pathogen, causing a variety of skin and soft tissue infections in healthy people and more virulent and invasive and disseminated diseases in immunocompromised humans. We study how C. albicans forms biofilms, how it interacts with host cells and members of the human microflora, and how its transcription circuits and RNA splicing patterns have been adapted for life in a mammalian host.