CO 2 Signaling through the Ptc2-Ssn3 Axis Governs Sustained Hyphal Development of Candida albicans by Reducing Ume6 Phosphorylation and Degradation

The capacity to sense and adapt to changing carbon dioxide levels is crucial for all organisms. In fungi, CO 2 is a key determinant involved in fundamental biological processes, including growth, morphology, and virulence. In the pathogenic fungus Candida albicans , high CO 2 is directly sensed by adenylyl cyclase to promote hyphal growth. However, little is known about the mechanism by which hyphal development is maintained in response to physiological levels of CO 2 . Here we report that a signal transduction system mediated by a phosphatase-kinase pair controls CO 2 -responsive Ume6 phosphorylation and stability that in turn dictate hyphal elongation. Our results unravel a new regulatory mechanism of CO 2 signaling in fungi.