The Hsp90 co-chaperone Sgt1 governs Candida albicans morphogenesis and drug resistance.
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The molecular chaperone Hsp90 orchestrates regulatory circuitry governing fungal morphogenesis, biofilm development, drug resistance, and virulence. Hsp90 functions in concert with co-chaperones to regulate stability and activation of client proteins, many of which are signal transducers. Here, we characterize the first Hsp90 co-chaperone in the leading human fungal pathogen, Candida albicans. We demonstrate that Sgt1 physically interacts with Hsp90, and that it governs C. albicans morphogenesis and drug resistance. Genetic depletion of Sgt1 phenocopies depletion of Hsp90, inducing yeast to filament morphogenesis and invasive growth. Sgt1 governs these traits by bridging two morphogenetic regulators: Hsp90 and the adenylyl cyclase of the cAMP-PKA signaling cascade, Cyr1. Sgt1 physically interacts with Cyr1, and depletion of either Sgt1 or Hsp90 activates cAMP-PKA signaling, revealing the elusive link between Hsp90 and the PKA signaling cascade. Sgt1 also mediates tolerance and resistance to the two most widely deployed classes of antifungal drugs, azoles and echinocandins. Depletion of Sgt1 abrogates basal tolerance and acquired resistance to azoles, which target the cell membrane. Depletion of Sgt1 also abrogates tolerance and resistance to echinocandins, which target the cell wall, and renders echinocandins fungicidal. Though Sgt1 and Hsp90 have a conserved impact on drug resistance, the underlying mechanisms are distinct. Depletion of Hsp90 destabilizes the client protein calcineurin, thereby blocking crucial responses to drug-induced stress; in contrast, depletion of Sgt1 does not destabilize calcineurin, but blocks calcineurin activation in response to drug-induced stress. Sgt1 influences not only morphogenesis and drug resistance, but also virulence, as genetic depletion of C. albicans Sgt1 leads to reduced kidney fungal burden in a murine model of systemic infection. Thus, our characterization of the first Hsp90 co-chaperone in a fungal pathogen establishes C. albicans Sgt1 as a global regulator of morphogenesis and drug resistance, providing a new target for treatment of life-threatening fungal infections.
Cyclic AMP-Dependent Protein Kinases
Drug Resistance, Fungal
HSP90 Heat-Shock Proteins
Published Version (Please cite this version)10.1371/journal.pone.0044734
Publication InfoShapiro, RS; Zaas, Aimee Kirsch; Betancourt-Quiroz, M; Perfect, John Robert; & Cowen, LE (2012). The Hsp90 co-chaperone Sgt1 governs Candida albicans morphogenesis and drug resistance. PLoS One, 7(9). pp. e44734. 10.1371/journal.pone.0044734. Retrieved from http://hdl.handle.net/10161/15369.
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James B. Duke Professor of Medicine
Research in my laboratory focuses around several aspects of medical mycology. We are investigating antifungal agents (new and old) in animal models of candida and cryptococcal infections. We have examined clinical correlation of in vitro antifungal susceptibility testing and with in vivo outcome. Our basic science project examines the molecular pathogenesis of cryptococcal infections. We have developed a molecular foundation for C. neoformans, including transformation systems, gene disr
Associate Professor of Medicine
Medical education Genomic applications for diagnosis of infectious diseases Genomic applications for prediction of infectious diseases
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