C. albicans Hsp90

Candida albicans is an opportunistic fungal pathogen in humans that commonly causes irritation of the mucosal epithelia. Heat shock proteins (HSP) are a family of proteins that are produced by cells in response to exposure to stressful conditions.

Hsp90 is an essential molecular chaperone that responds to environmental cues and regulates the form and function of its target proteins. Hsp90 has a number of different functions. Many Hsp90 proteins are regulators of cellular signalings, such as kinases and transcription factors, which dwell in incompletely folded or aggregation-prone states. As a heat shock protein, Hsp90 is induced under conditions of stress, such as increased temperature; however, global problems in protein folding that occur at elevated temperature can overwhelm Hsp90 chaperone function. Therefore, as a thermally responsive chaperone that regulates key signal transducers, Hsp90 is uniquely poised to govern temperature-dependent traits, such morphogenesis in C. albicans.

Compromising Hsp90 function induces a transition from yeast to filamentous growth in C. albicans, even in the absence of external cues. Hsp90 is a key temperature sensor that governs C. albicans morphogenesis such that elevated temperature is required to relieve Hsp90-mediated repression of the morphogenetic program.