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Genetic Interactions Between Aspergillus fumigatus Basic Leucine Zipper (bZIP) Transcription Factors AtfA, AtfB,
Lilian Pereira Silva1, Maria Augusta Crivelente Horta1, Gustavo Henrique Goldman1
1Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.
Abstract:
Aspergillus fumigatus is an opportunistic fungus, capable of causing Invasive Aspergillosis in immunocompromised patients, recently transplanted or undergoing chemotherapy. In the present work, we continued the investigation on A. fumigatus AtfA-D transcription factors (TFs) characterizing possible genetic and physical interactions between them after normal growth and stressing conditions. We constructed double null mutants for all the possible combinations of ΔatfA-, -B, -C, and -D, and look into their susceptibility to different stressing conditions. Our results indicate complex genetic interactions among these TFs that could impact the response to different kinds of stressful conditions. AtfA-D interactions also affect the A. fumigatus virulence in Galleria mellonella. AtfA:GFP is ~97% located in the nucleus while about 20-30% of AtfB, -C, and -D:GFP locate into the nucleus in the absence of any stress. Under stressing conditions, AtfB, -C, and -D:GFP translocate to the nucleus about 60-80% upon the addition of sorbitol or H2O2. These four TFs are also interacting physically forming all the possible combinations of heterodimers. We also identified that AtfA-D physically interact with the MAPK SakA in the absence of any stress and upon osmotic and cell wall stresses. They are involved in the accumulation of trehalose, glycogen and metabolic assimilation of different carbon sources.
Insights
Investigating Aspergillus fumigatus transcription factors AtfA-D reveals complex genetic and physical interactions. These interactions influence fungal virulence and stress responses, impacting trehalose and glycogen accumulation.
Area of Science:
- Mycology
- Molecular Biology
- Fungal Pathogenesis
Background:
- Aspergillus fumigatus is an opportunistic fungal pathogen causing invasive aspergillosis in immunocompromised individuals.
- Transcription factors (TFs) play crucial roles in fungal adaptation and virulence.
- Previous studies have initiated the characterization of AtfA-D TFs in A. fumigatus.
Purpose of the Study:
- To investigate the genetic and physical interactions among Aspergillus fumigatus transcription factors AtfA-D.
- To determine the role of AtfA-D interactions in fungal response to stress conditions.
- To assess the impact of AtfA-D interactions on A. fumigatus virulence and TF localization.
Main Methods:
- Construction and analysis of double null mutants for all combinations of ΔatfA, ΔatfB, ΔatfC, and ΔatfD.
- Assessment of fungal susceptibility to various stressing conditions (e.g., sorbitol, H2O2).
- Subcellular localization studies using fluorescently tagged TFs (AtfA:GFP, AtfB:GFP, etc.) under normal and stress conditions.
- Co-immunoprecipitation assays to identify physical interactions between AtfA-D TFs and the MAPK SakA.
Main Results:
- Complex genetic interactions among AtfA-D TFs were identified, affecting stress response.
- AtfA-D TF interactions were shown to influence A. fumigatus virulence in Galleria mellonella.
- AtfA:GFP predominantly localized to the nucleus, while AtfB, -C, and -D:GFP showed dynamic nuclear translocation (20-80%) under stress.
- All possible heterodimers of AtfA-D were found to interact physically.
- AtfA-D TFs physically interact with MAPK SakA under normal and stress conditions.
- These TFs are involved in trehalose and glycogen accumulation and carbon source metabolism.
Conclusions:
- The AtfA-D transcription factors exhibit intricate genetic and physical interactions crucial for Aspergillus fumigatus stress adaptation and virulence.
- Nuclear localization of AtfB, -C, and -D is regulated by stress, highlighting their dynamic roles.
- Interactions with MAPK SakA suggest a role in stress signaling pathways.
- These TFs collectively regulate key metabolic processes, including carbohydrate storage and utilization.
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