At the site of infection, the human fungal pathogen Aspergillus fumigatus faces abrupt changes in oxygen concentrations. An increasing number of studies have demonstrated that elevated production of intracellular reactive oxygen species (ROS) under low oxygen conditions plays a regulatory role in modulating cellular responses for adaptation to hypoxia. To learn more about this process in A. fumigatus, we determined intracellular ROS production during hypoxia. Our results confirmed increased amounts of intracellular ROS in A. fumigatus exposed to decreased oxygen levels. Moreover, nuclear accumulation of the major oxidative stress regulator AfYap1 was observed after low oxygen cultivation. For further analysis, we applied iodoTMT labelling of redox-sensitive cysteine residues to identify proteins that are reversibly oxidised. This analysis revealed that proteins with important roles in maintaining redox balance and protein folding, such as the thioredoxin Asp f 29 and the protein disulphide PdiA, underwent substantial thiol modification under hypoxia. Our data also showed that the mitochondrial respiratory complex IV assembly protein Coa6 was significantly oxidised by hypoxic ROS. Deletion of the corresponding gene resulted in a complete absence of hypoxic growth, indicating the importance of complex IV during adaptation of A. fumigatus to oxygen-limiting conditions. This article is protected by copyright. All rights reserved
Bibliographical noteWe thank Silke Steinbach, Till Kindel, and Michael Cyrulies for their excellent technical assistance. Work of T.K., O.K. and A.A.B was supported by the Deutsche Forschungsge-meinschaft within the Collaborative Research Center TR124 FungiNet (project A1 and Z2).The work of E.S. was supported by the International Leibniz Research School for Microbial and Biomolecular Interactions (ILRS)and by the Medical Research Council Centre for Medical Mycology at the University of Aberdeen (MR/N006364/1).We thank Matthew Blango and Falk Hillmann for the critical reading of the manuscript.
- redox homeostasis