Phosphorylation of Calcineurin at a novel serine-proline rich region orchestrates hyphal growth and virulence in Aspergillus fumigatus.

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Version: Final published version
Serval ID
serval:BIB_22DC18385DF3
Type
Article: article from journal or magazin.
Collection
Publications
Title
Phosphorylation of Calcineurin at a novel serine-proline rich region orchestrates hyphal growth and virulence in Aspergillus fumigatus.
Journal
Plos Pathogens
Author(s)
Juvvadi P.R., Gehrke C., Fortwendel J.R., Lamoth F., Soderblom E.J., Cook E.C., Hast M.A., Asfaw Y.G., Moseley M.A., Creamer T.P., Steinbach W.J.
ISSN
1553-7374 (Electronic)
ISSN-L
1553-7366
Publication state
Published
Issued date
2013
Volume
9
Number
8
Pages
e1003564
Language
english
Notes
Publication types: Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
Publication Status: ppublish
Abstract
The fungus Aspergillus fumigatus is a leading infectious killer in immunocompromised patients. Calcineurin, a calmodulin (CaM)-dependent protein phosphatase comprised of calcineurin A (CnaA) and calcineurin B (CnaB) subunits, localizes at the hyphal tips and septa to direct A. fumigatus invasion and virulence. Here we identified a novel serine-proline rich region (SPRR) located between two conserved CnaA domains, the CnaB-binding helix and the CaM-binding domain, that is evolutionarily conserved and unique to filamentous fungi and also completely absent in human calcineurin. Phosphopeptide enrichment and tandem mass spectrometry revealed the phosphorylation of A. fumigatus CnaA in vivo at four clustered serine residues (S406, S408, S410 and S413) in the SPRR. Mutation of the SPRR serine residues to block phosphorylation led to significant hyphal growth and virulence defects, indicating the requirement of calcineurin phosphorylation at the SPRR for its activity and function. Complementation analyses of the A. fumigatus ΔcnaA strain with cnaA homologs from the pathogenic basidiomycete Cryptococcus neoformans, the pathogenic zygomycete Mucor circinelloides, the closely related filamentous fungi Neurospora crassa, and the plant pathogen Magnaporthe grisea, revealed filamentous fungal-specific phosphorylation of CnaA in the SPRR and SPRR homology-dependent restoration of hyphal growth. Surprisingly, circular dichroism studies revealed that, despite proximity to the CaM-binding domain of CnaA, phosphorylation of the SPRR does not alter protein folding following CaM binding. Furthermore, mutational analyses in the catalytic domain, CnaB-binding helix, and the CaM-binding domains revealed that while the conserved PxIxIT substrate binding motif in CnaA is indispensable for septal localization, CaM is required for its function at the hyphal septum but not for septal localization. We defined an evolutionarily conserved novel mode of calcineurin regulation by phosphorylation in filamentous fungi in a region absent in humans. These findings suggest the possibility of harnessing this unique SPRR for innovative antifungal drug design to combat invasive aspergillosis.
Keywords
Amino Acid Motifs, Animals, Antifungal Agents/chemistry, Antifungal Agents/therapeutic use, Aspergillosis/drug therapy, Aspergillosis/enzymology, Aspergillus fumigatus/enzymology, Aspergillus fumigatus/genetics, Calcineurin/chemistry, Calcineurin/immunology, Calcineurin Inhibitors, Fungal Proteins/antagonists & inhibitors, Fungal Proteins/chemistry, Humans, Hyphae/enzymology, Hyphae/genetics, Male, Mice, Models, Biological, Phosphorylation, Protein Structure, Tertiary
Pubmed
Web of science
Open Access
Yes
Create date
11/10/2016 16:05
Last modification date
20/08/2019 13:00
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