ABSTRACT: Aspergillus fumigatus, a common airborne fungus, has been reported as one of the most frequent agents of human fungal infections. However, A. fumigatus conidia atmospheric resistance and longevity, and their aging mechanism are unknown. Therefore, the main purpose of this work is to clarify the main processes associated with conidial adaptation to nutrient limitation, similar to those found in their atmospheric transport. To that a time course evaluation of the changes in the proteome and in the ultrastructure of A. fumigatus’ conidia subjected to limiting nutrient conditions were performed, allowing a comprehensive characterization of conidia cells behavior and, revealing possible targets for the development of new antifungal medicines and improve infection control strategies. In the proposed work, a total of 712 proteins were identified and compared in the A. fumigatus conidia, with 387 proteins presenting significant differences among the considered conditions. These 387 proteins were then grouped into clusters according to similarities in their dynamic profile (relative levels) among the three points in time analyzed, and four completely distinct profiles can be observed. According with the proteomics changes, it was observed that the conidia go from a highly active metabolic state to a dormant state, and culminate in a cell autolysis state revealed by increased levels of hydrolytic enzymes. The proteomics alterations observed were further corroborate with the structural results, where it was observed changes in mitochondria, nucleus, and plasma membrane ultrastructure, consistent with an apoptotic process. Altogether the results indicate that the changes in protein levels anticipated those in cell morphology, clearly highlighting the need for further studies that may lead to significant improvement in infection control strategies. Additionally, a total of 28 proteins were identified with one acetylated peptide. Among them, it was possible to quantify the acetylation levels in 21 proteins with 11 presenting a statistical meaningful difference between the tested time points. Furthermore, from the proteins evaluated, all except the protein Histone H3, presented N-terminal acetylation. In the case of the Histone H3, the modification was observed at the lysine 56. In general, the proteins regulated by acetylation quantified in our study could be grouped into four distinct groups and although only some of the proteins have a statistical meaningful variation between the experimental time points, those proteins are spread along the different groups. Moreover, statistical variation if observed for all the proteins belonging to the group of proteins that have higher acetylation levels at time 15 minutes. In conclusion, this work presents a comprehensive characterization of the proteomics changes associated with the adaptive mechanism of Aspergillus fumigatus’ conidia to nutrient restriction, raveling some on the main pathways associated with such capacity. Furthermore, this proteomic characterization is associated with the conidia’s ultrastructural evaluation allowing to link the changes observed at the proteome level with the respective phenotype. Finally, it was also presented an evaluation of the levels of the protein acetylation, one of the principal regulatory PTMs in eukaryotes. Therefore, the present study may be an important dataset to be used as a tool to understand and identified potential targets associated with conidia resistance, and therefore improving infection control strategies.
Sandra Anjo 
