Molecular Dissection of Crz1 and Its Dynamic Subcellular Localization in Cryptococcus neoformans

Abstract

Across lower eukaryotes, the transcription factor Crz1 is dephosphorylated by calcineurin, which facilitates Crz1 translocation to the nucleus to regulate gene expression. In the fungal pathogen Cryptococcus neoformans, calcineurin–Crz1 signaling maintains calcium homeostasis, thermotolerance, cell wall integrity, and morphogenesis. How Crz1 distinguishes different stressors and differentially regulates cellular responses is poorly understood. Through monitoring Crz1 subcellular localization over time, we found that Crz1 transiently localizes to granules after exposure to high temperature or calcium. These granules also host the phosphatase calcineurin and Pub1, a ribonucleoprotein stress granule marker, suggesting a role of stress granules in modulating calcineurin–Crz1 signaling. Additionally, we constructed and analyzed an array of Crz1 truncation mutants. We identified the intrinsically disordered regions in Crz1 contribute to proper stress granule localization, nuclear localization, and function. Our results provide the groundwork for further determination of the mechanisms behind the complex regulation of Crz1.