Protein kinase A signaling in Aspergillus fumigatus: Identification of downstream targets

Juliane Macheleidt, Wolfgang Schmidt-Heck, Ilse D.Jacobsen , Thorsten Heinekamp, Axel A. Brakhage

Author address: 

Leibniz Institute for Natural Product Research and Infection Biology - Hans-Knöll-Institute, Molecular and Applied Microbiology, Jena, Germany

Abstract: 

Aspergillus fumigatus is a saprophytic mould normally inhabiting the soil. The fungus also represents a medically important pathogen causing severe systemic infections in immunocompromised patients. To survive in these entirely different habitats, A. fumigatus needs mechanisms to sense environmental signals and transduce them intracellularly. One of these signal transduction pathways is the cAMP dependent protein kinase A (PKA) pathway. For A. fumigatus, components of this signaling cascade have been characterized in detail and its significance for virulence is evident. To identify target genes of PKA, we performed microarray analyses using a mutant strain overproducing the PKA catalytic subunit. Following this approach, 23 transcription factors potentially regulated by PKA were identified. From these, 15 were deleted and the mutant phenotypes were characterized. A gene encoding a C6 finger domain protein that showed highest upregulation of all identified transcription factors is located in a potential secondary metabolite gene cluster. Deletion of the transcription factor gene resulted in reduced growth and sporulation of the mutant strain. This phenotype was observed even more drastically for a strain lacking the nonribosomal peptide synthetase of the same cluster. Because genes of this cluster were shown to be transcribed in infected mouse lungs, a virulence study was performed using an embryonated egg infection model. However, the transcription factor deletion mutant showed no altered virulence compared to the corresponding wild type. To get deeper insights into the function of the secondary metabolite gene cluster, the gene encoding the C6 finger domain protein was overexpressed using an inducible promoter. Overproduction of the transcription factor resulted in induced transcription of all cluster genes and furthermore in the formation of a brown substance which is currently under investigation
2013

abstract No: 

359

Full conference title: 

27th Fungal Genetics Conference
    • Fungal Genetics Conference 27th (2013)