The Aspergillus fumigatus transcriptional regulator

for defense against reactive oxygen intermediates but is dispensable for pathogenicity in an 2 intranasal mouse infection model 3 4 Abstract 1 Macrophages and neutrophils kill the airborne fungal pathogen Aspergillus fumigatus. The 2 dependency of this killing process on reactive oxygen intermediates (ROI) was strongly 3 suggested. Therefore, we investigated the enzymatic ROI detoxifying system by proteome 4 analysis of A. fumigatus challenged by H 2 O 2. Since many of the identified proteins / genes are 5 apparently regulated by a putative Saccharomyces cerevisiae Yap1 homolog, the corresponding 6 gene of A. fumigatus was identified and designated Afyap1. Nuclear localization of a functional 7 AfYap1-eGFP fusion was stress dependent. Deletion of the Afyap1 gene led to drastically 8 increased sensitivity of the deletion mutant against H 2 O 2 and menadione, but not diamide and 9 NO radicals. Proteome analysis of the ∆Afyap1 mutant strain challenged with 2 mM H 2 O 2 10 indicated that 29 proteins are controlled directly or indirectly by AfYap1 including catalase 2. 11 Despite its importance for defense against reactive agents, the Afyap1 deletion mutant did not 12 show attenuated virulence in a murine model of Aspergillus infection. These data challenge the 13 hypothesis that ROI such as superoxide anions and peroxides play a direct role in killing of A. 14 fumigatus in an immunocompromised host. This conclusion was further supported by the finding 15 that killing of A. fumigatus wild-type and ∆Afyap1 mutant germlings by human neutrophilic 16 granulocytes worked equally well irrespective whether the ROI scavenger glutathione or an 17 NADPH-oxidase inhibitor was added to the cells.