This Article Full Text (PDF) Other Versions of this Article: EC.00224-07v1 6/12/2437    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Richie, D. L. Articles by Askew, D. S. Search for Related Content PubMed PubMed Citation Articles by Richie, D. L. Articles by Askew, D. S.

 Previous Article  |  Next Article 

Eukaryotic Cell doi:10.1128/EC.00224-07
Copyright (c) 2007, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

An unexpected link between metal ion deficiency and autophagy in Aspergillus fumigatus

Department of Pathology & Laboratory Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0529, Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, Department of Microbiology and Immunology, Albert Einstein College of, Medicine, Bronx, New York, Department of Obstetrics & Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, New York 10461

^* To whom correspondence should be addressed. Email: David.Askew{at}uc.edu.

	Abstract

Autophagy is the major cellular pathway for bulk degradation of cytosolic material and is required to maintain viability during starvation conditions. To determine the contribution of autophagy to starvation stress responses in the filamentous fungus Aspergillus fumigatus we disrupted the A. fumigatus atg1 gene, encoding a serine/threonine kinase required for autophagy. The Afatg1 mutant showed abnormal conidiophore development and reduced conidiation, but the defect could be bypassed by increasing the nitrogen content of the medium. When transferred to starvation medium, wild type hyphae were able to undergo a limited amount of growth, resulting in radial expansion of the colony. By contrast, the Afatg1 mutant was unable to grow under these conditions. However, supplementation of the medium with metal ions rescued the ability of the Afatg1 mutant to grow in the absence of a carbon or nitrogen source. Depleting medium of cations using EDTA was sufficient to induce autophagy in wild type A. fumigatus, even in the presence of abundant carbon and nitrogen, and the Afatg1 mutant was severely growth impaired under these conditions. These findings establish a role for autophagy in the recycling of internal nitrogen sources to support conidiophore development, and suggest that autophagy also contributes to the recycling of essential metal ions to sustain hyphal growth when exogenous nutrients are scarce.