Functional analysis of the superoxide dismutase family in Aspergillus fumigatus

K Lambou, C Lamarre, R Beau, N Dufour… - Molecular …, 2010 - Wiley Online Library
K Lambou, C Lamarre, R Beau, N Dufour, JP Latge
Molecular microbiology, 2010Wiley Online Library
Reactive oxidant species produced by phagocytes have been reported as being involved in
the killing of Aspergillus fumigatus. Fungal superoxide dismutases (SODs) that detoxify
superoxide anions could be putative virulence factors for this opportunistic pathogen. Four
genes encoding putative Sods have been identified in the A. fumigatus genome: a
cytoplasmic Cu/ZnSOD (AfSod1p), a mitochondrial MnSOD (AfSod2p), a cytoplasmic
MnSOD (AfSod3p) and AfSod4 displaying a MnSOD C‐terminal domain. During growth …
Summary
Reactive oxidant species produced by phagocytes have been reported as being involved in the killing of Aspergillus fumigatus. Fungal superoxide dismutases (SODs) that detoxify superoxide anions could be putative virulence factors for this opportunistic pathogen. Four genes encoding putative Sods have been identified in the A. fumigatus genome: a cytoplasmic Cu/ZnSOD (AfSod1p), a mitochondrial MnSOD (AfSod2p), a cytoplasmic MnSOD (AfSod3p) and AfSod4 displaying a MnSOD C‐terminal domain. During growth, AfSOD1 and AfSOD2 were highly expressed in conidia whereas AfSOD3 was only strongly expressed in mycelium. AfSOD4 was weakly expressed compared with other SODs. The deletion of AfSOD4 was lethal. Δsod1 and Δsod2 mutants showed a growth inhibition at high temperature and a hypersensitivity to menadione whereas the sod3 mutant had only a slight growth delay at high temperature. Multiple mutations had only an additive effect on the phenotype. The triple sod1/sod2/sod3 mutant was characterized by a delay in conidial germination, a reduced conidial survival during storage overtime, the highest sensitivity to menadione and an increased sensitivity to killing by alveolar macrophage of immunocompetent mice. In spite of these phenotypes, no significant virulence difference was observed between the triple mutant and parental strain in experimental murine aspergillosis models in immunocompromised animals.
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