Systematic Global Analysis of Genes Encoding Protein Phosphatases inAspergillus fumigatus

Abstract

Aspergillus fumigatus is a fungal pathogen that causes several invasive and noninvasive diseases named aspergillosis. This disease is generally regarded as multifactorial, considering that several pathogenicity determinants are present during the establishment of this illness. It is necessary to obtain an increased knowledge of how, and which, A. fumigatus signal transduction pathways are engaged in the regulation of these processes. Protein phosphatases are essential to several signal transduction pathways. We identified 32 phosphatase catalytic subunit-encoding genes in A. fumigatus, of which we were able to construct 24 viable deletion mutants. The role of nine phosphatase mutants in the HOG (high osmolarity glycerol response) pathway was evaluated by measuring phosphorylation of the p38 MAPK (SakA) and expression of osmo-dependent genes. We were also able to identify 11 phosphatases involved in iron assimilation, six that are related to gliotoxin resistance, and three implicated in gliotoxin production. These results present the creation of a fundamental resource for the study of signaling in A. fumigatus and its implications in the regulation of pathogenicity determinants and virulence in this important pathogen.

The Aspergillus fumigatus SchASCH9 kinase modulates SakAHOG1 MAP kinase activity and it is essential for virulence

“…We have previously shown in a time course kinetics (10–60 min exposure to 1 M sorbitol) that 10 min is the timepoint with the highest SakA phosphorylation when A. fumigatus is exposed to 1 M sorbitol (Hagiwara et al ., ). The reduction of SakA phosphorylation in the wild‐type strain after 10 min is due to SakA modulation by dephosphorylation by SakA phosphatases (Winkelströter et al ., ). The Δ schA mutant has increased levels of SakA phosphorylation upon osmotic stress (Fig.…”

Aspergillus fumigatusprotein phosphatase PpzA is involved in iron assimilation, secondary metabolite production, and virulence

“…Previously, we have observed reduced mRNA accumulation of sidA and hapX in the Δ ppzA mutant when compared to the wild‐type strain by using RT‐qPCR experiments (Winkelströter et al, ). We have used as normalizer for this set of qRT‐PCR experiments AFUB_010330/Afu1g10910 encoding the beta‐tubulin.…”

“…As previously shown (Winkelströter et al ., ), A . fumigatus ΔppzA has comparable growth to the wild‐type and complementing strains in minimal media (MM, Figure a,b); however, it has reduced growth when grown in iron starvation conditions (Figure b).…”

“…Recently, we have characterised several A . fumigatus protein phosphatase null mutants that are associated to iron assimilation because they have reduced growth during iron starvation (Winkelströter et al, ). Among these protein phosphatases, we have identified the gene ppzA that codes for the catalytic subunit of PPZ and it was previously shown to be involved in oxidative stress tolerance (Leiter et al, ; Muszkieta et al, ).…”

“…Aspergillus fumigatus PpzA, the catalytic subunit of protein phosphatase Z (PPZ), has been recently identified as associated with iron assimilation (Winkelströter et al, ). Null ppzA mutants have reduced biomass accumulation upon iron starvation conditions (Winkelströter et al, ). The gene ppzA is regulated by the Skn7 transcription factor, and it is involved in corneal infection by A .…”