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Eukaryotic Cell, March 2009, p. 271-277, Vol. 8, No. 3
1535-9778/09/$08.00+0     doi:10.1128/EC.00391-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Deletion of the Protein Kinase A Regulatory Subunit Leads to Deregulation of Mitochondrial Activation and Nuclear Duplication in Aspergillus fumigatus{triangledown}

Kevin K. Fuller, Wei Zhao,{dagger} David S. Askew, and Judith C. Rhodes*

Department of Pathology and Laboratory Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, Ohio 45267-0529

Received 18 December 2008/ Accepted 28 December 2008

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 {Delta}pkaR 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, {Delta}pkaR 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 {Delta}pkaR 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.

* Corresponding author. Mailing address: Dept. of Pathology, University of Cincinnati, P.O. Box 670529, Cincinnati, OH 45267-0529. Phone: (513) 558-0130. Fax: (513) 558-8687. E-mail: Judith.rhodes{at}uc.edu

{triangledown} Published ahead of print on 5 January 2009.

{dagger} Present address: Department of Medical Microbiology, College of Medical Sciences, Qingdao University, 308 Ningxia Road, Qingdao, Shangdong 266071, People's Republic of China.

Eukaryotic Cell, March 2009, p. 271-277, Vol. 8, No. 3
1535-9778/09/$08.00+0     doi:10.1128/EC.00391-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





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