title: Deletion of the protein kinase A regulatory subunit leads to deregulation of mitochondrial activation and nuclear duplication in Aspergillus fumigatus.
abstract: Proper regulation of the cyclic AMP-dependent protein kinase (PKA) pathway is required for normal growth and development in many fungi. We have reported that deletion of the PKA regulatory subunit gene, pkaR, in Aspergillus fumigatus leads to defects in germination and a hypersensitivity of conidia to oxidative stress. In this study, we further analyzed the defects of DeltapkaR conidia and found that a large proportion were abnormally larger than wild type. Because swelling and increased susceptibility to oxidative stress are characteristic of germinating conidia, we analyzed the metabolic activity of the conidia by mitochondrial staining. Whereas it required 4 h in rich medium for wild-type mitochondria to become active, DeltapkaR conidia harbored active mitochondria in the absence of a germinant. Furthermore, conidia of the mutant showed a dramatic loss in viability upon short-term storage in water, indicating starvation-induced death. Taken together, our data suggest that PKA activity regulates metabolic activation of resting conidia. Additionally, the DeltapkaR mutant displayed an abnormal abundance of hyphal nuclei and had increased transcript levels of several cell cycle regulatory genes. These data indicate an important role for PKA in the nuclear duplication cycle of A. fumigatus.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0529, USA.
authors.forename: Kevin K
authors.initials: KK
authors.lastname: Fuller
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: David S
authors.initials: DS
authors.lastname: Askew
authors.forename: Judith C
authors.initials: JC
authors.lastname: Rhodes
mesh_terms: D001232:Aspergillus fumigatus / Q000737:chemistry / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D048750:Cell Nucleus Division; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D013172:Spores, Fungal / Q000737:chemistry / Q000166:cytology / Q000201:enzymology / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D021122:Protein Subunits; D017868:Cyclic AMP-Dependent Protein Kinases