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Eukaryotic Cell, December 2005, p. 1982-1989, Vol. 4, No. 12
1535-9778/05/$08.00+0 doi:10.1128/EC.4.12.1982-1989.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
A Fungus-Specific Ras Homolog Contributes to the Hyphal Growth and Virulence of Aspergillus fumigatus
Jarrod R. Fortwendel,1
Wei Zhao,1
Ruchi Bhabhra,1
Steven Park,2
David S. Perlin,2
David S. Askew,1 and
Judith C. Rhodes1*
Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio,1
Public Health Research Institute, Newark, New Jersey2
Received 14 June 2005/
Accepted 26 September 2005
The Ras family of GTPase proteins has been shown to control morphogenesis in many organisms, including several species of pathogenic fungi. In a previous study, we identified a gene encoding a fungus-specific Ras subfamily homolog, rasB, in Aspergillus fumigatus. Here we report that deletion of A. fumigatus rasB caused decreased germination and growth rates on solid media but had no effect on total biomass accumulation after 24 h of growth in liquid culture. The
rasB mutant had an irregular hyphal morphology characterized by increased branching. Expression of rasB
113-135, a mutant transgene lacking the conserved rasB internal amino acid insertion, did not complement the deletion phenotype of delayed growth and germination rates and abnormal hyphal morphology. Virulence of the rasB deletion strain was diminished; mice infected with this strain exhibited
65% survival compared to
10% with wild-type and reconstituted strains. These data support the hypothesis that rasB homologs, which are highly conserved among fungi that undergo hyphal growth, control signaling modules important to the directional growth of fungal hyphae.
* Corresponding author. Mailing address: University of Cincinnati, College of Medicine, 231 Albert Sabin Way, Cincinnati, OH 45267-0529. Phone: (513) 558-0130. Fax: (513) 558-2289. E-mail: Judith.Rhodes{at}uc.edu.
Eukaryotic Cell, December 2005, p. 1982-1989, Vol. 4, No. 12
1535-9778/05/$08.00+0 doi:10.1128/EC.4.12.1982-1989.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
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Copyright © 2005 by the American Society for Microbiology.