Putative Membrane Receptors Contribute to Activation and Efficient Signaling of Mitogen-Activated Protein Kinase Cascades during Adaptation of Aspergillus fumigatus to Different Stressors and Carbon Sources

Author(s)

Silva, Lilian Pereira ^[1] ; Frawley, Dean ^[2] ; de Assis, Leandro Jose ^[1] ; Tierney, Ciara ^[2] ; Fleming, Alastair B. ^[3] ; Bayram, Ozgur ^[2] ; Goldman, Gustavo Henrique ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Sao Paulo - Brazil

^[2] Maynooth Univ, Biol Dept, Maynooth, Kildare - Ireland

^[3] Trinity Coll Dublin, Sch Genet & Microbiol, Moyne Inst Prevent Med, Dept Microbiol, Dublin - Ireland

• Document type: Journal article
• Source: MSPHERE; v. 5, n. 5 SEP-OCT 2020.
• Web of Science Citations: 0

Abstract

The high-osmolarity glycerol (HOG) response pathway is a multifunctional signal transduction pathway that specifically transmits ambient osmotic signals. Saccharomyces cerevisiae Hog1p has two upstream signaling branches, the sensor histidine kinase SIn1p and the receptor Sho1p. The Sho1p branch includes two other proteins, the Msb2p mucin and Opy2p. Aspergillus fumigatus is the leading cause of pulmonary fungal diseases. Here, we investigated the roles played by A. fumigatus SlnA(Sln)(1p), ShoA(Sho1p), MsbA(Msb)(2p), and OpyA(O)(pY)(2p) putative homologues during the activation of the mitogen-activated protein kinase (MAPK) HOG pathway. The shoA, msbA, and opyA singly and doubly null mutants are important for the cell wall integrity (CWI) pathway, oxidative stress, and virulence as assessed by a Galleria mellonella model. Genetic interactions of ShoA, MsbA, and OpyA are also important for proper activation of the SakA(Hog)(1p) and MpkA(Slt2) cascade and the response to osmotic and cell wall stresses. Comparative label-free quantitative proteomics analysis of the singly null mutants with the wild-type strain upon caspofungin exposure indicates that the absence of ShoA, MsbA, and OpyA affects the osmotic stress response, carbohydrate metabolism, and protein degradation. The putative receptor mutants showed altered trehalose and glycogen accumulation, suggesting a role for ShoA, MsbA, and OpyA in sugar storage. Protein kinase A activity was also decreased in these mutants. We also observed genetic interactions between SInA, ShoA, MsbA, and OpyA, suggesting that both branches are important for activation of the HOG/CWI pathways. Our results help in the understanding of the activation and modulation of the HOG and CWI pathways in this important fungal pathogen. IMPORTANCE Aspergillus fumigatus is an important human-pathogenic fungal species that is responsible for a high incidence of infections in immunocompromised individuals. A. fumigatus high-osmolarity glycerol (HOG) and cell wall integrity pathways are important for the adaptation to different forms of environmental adversity such as osmotic and oxidative stresses, nutrient limitations, high temperatures, and other chemical and mechanical stresses that may be produced by the host immune system and antifungal drugs. Little is known about how these pathways are activated in this fungal pathogen. Here, we characterize four A. fumigatus putative homologues that are important for the activation of the yeast HOG pathway. A. fumigatus SInA(Sln)(1p), ShoA(Sho)(1p), MsbA(Msb)(2p), and OpyA(O)(Py)(2p) are genetically interacting and are essential for the activation of the HOG and cell wall integrity pathways. Our results contribute to the understanding of A. fumigatus adaptation to the host environment. (AU)

• FAPESP's process: 16/07870-9 - The influence of mitogen activated protein kinases (MAPK) on the expression of genetic determinants important for Aspergillus fumigatus virulence
• Grantee: Gustavo Henrique Goldman
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/00789-6 - Functional characterization of Aspergillus nidulans phosphatases involved on glucose metabolism
• Grantee: Leandro Jose de Assis
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 16/21392-2 - "Characterization of transcription factors that have the basic domain" zipper "leucine (bZIP) ATF1 in Aspergillus fumigatus"
• Grantee: Lilian Pereira Silva
• Support Opportunities: Scholarships in Brazil - Doctorate