Calcineurin-dependent dephosphorylation of the transcription factor CrzA at specific sites controls conidiation, stress tolerance, and virulence of Aspergillus fumigatus.

Published online

Journal Article

Calcium signaling through calcineurin and its major transcription factor (TF), CrzA, is integral to hyphal growth, stress response and virulence of the pathogenic fungus Aspergillus fumigatus, the leading etiology of invasive aspergillosis. Dephosphorylation of CrzA by calcineurin activates the TF, but the specific phosphorylation sites and their roles in the activation/inactivation mechanism are unknown. Mass spectroscopic analysis identified 20 phosphorylation sites, the majority of which were specific to filamentous fungi and distributed throughout the CrzA protein, with particular concentration in a serine-rich region N-terminal to the conserved DNA-binding domain (DBD). Site-directed mutagenesis of phosphorylated residues revealed that CrzA activity during calcium stimulation can only be suppressed by a high degree of phosphorylation in multiple regions of the protein. Our findings further suggest that this regulation is not solely accomplished through control of CrzA nuclear import. Additionally, we demonstrate the importance of the CrzA phosphorylation state in regulating growth, conidiation, calcium and cell wall stress tolerance, and virulence. Finally, we identify two previously undescribed nuclear localization sequences in the DBD. These findings provide novel insight into the phosphoregulation of CrzA which may be exploited to selectively target A. fumigatus.

Full Text

Duke Authors

Cited Authors

  • Shwab, EK; Juvvadi, PR; Waitt, G; Soderblom, EJ; Barrington, BC; Asfaw, YG; Moseley, MA; Steinbach, WJ

Published Date

  • March 29, 2019

Published In

PubMed ID

  • 30927289

Pubmed Central ID

  • 30927289

Electronic International Standard Serial Number (EISSN)

  • 1365-2958

Digital Object Identifier (DOI)

  • 10.1111/mmi.14254

Language

  • eng

Conference Location

  • England