ChIP‐seq reveals a role for CrzA in the Aspergillus fumigatus high‐osmolarity glycerol response (HOG) signalling pathway

• Published in: Molecular microbiology Vol. 94; no. 3; pp. 655 - 674
• Main Authors: Castro, Patrícia A., Chen, Chenxi, Almeida, Ricardo Sérgio Couto, Freitas, Fernanda Z., Bertolini, Maria C., Morais, Enyara Rezende, Brown, Neil Andrew, Ramalho, Leandra Naira Zambelli, Hagiwara, Daisuke, Mitchell, Thomas K., Goldman, Gustavo H.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.11.2014
• Subjects: Animals; Aspergillus fumigatus - genetics; Aspergillus fumigatus - growth & development; Aspergillus fumigatus - pathogenicity; Aspergillus fumigatus - physiology; Bacteria; Calcium; Chromatin; Chromatin Immunoprecipitation; Deoxyribonucleic acid; DNA; DNA, Fungal - chemistry; DNA, Fungal - genetics; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Deletion; Gene Expression Regulation, Fungal; Glycerol - metabolism; Kinases; Mammals; Mice; Osmolar Concentration; Osmotic Pressure; Phosphorylation; Protein Binding; Regulon; Sequence Analysis, DNA; Signal Transduction; Stress, Physiological; Virulence
• ISSN: 0950-382X; 1365-2958
• DOI: 10.1111/mmi.12785

Summary Aspergillus fumigatus is an opportunistic pathogen and allergen of mammals. Calcium signalling is essential for A. fumigatus pathogenicity and is regulated by the CrzA transcription factor. We used ChIP‐seq (Chromatin Immunoprecipitation DNA sequencing) to explore CrzA gene targets in A. fumigatus. In total, 165 potential binding peaks including 102 directly regulated genes were identified, resulting in the prediction of the A[GT][CG]CA[AC][AG] CrzA‐binding motif. The 102 CrzA putatively regulated genes exhibited a diverse array of functions. The phkB (Afu3g12530) histidine kinase and the sskB (Afu1g10940) MAP kinase kinase kinase of the HOG (high‐osmolarity glycerol response) pathway were regulated by CrzA. Several members of the two‐component system (TCS) and the HOG pathway were more sensitive to calcium. CrzA::GFP was translocated to the nucleus upon osmotic stress. CrzA is important for the phosphorylation of the SakA MAPK in response to osmotic shock. The ΔsskB was more sensitive to CaCl2, NaCl, and paraquat stress, while being avirulent in a murine model of invasive pulmonary aspergillosis. The presence of CaCl2 and osmotic stresses resulted in synergistic inhibition of ΔcrzA and ΔsskB growth. These results suggest there is a genetic interaction between the A. fumigatus calcineurin‐CrzA and HOG pathway that is essential for full virulence.