Transcription factor RonA-driven GlcNAc catabolism is essential for growth, cell wall integrity, and pathogenicity in Aspergillus fumigatus

TL;DR

The study reveals that the transcription factor RonA is crucial for breaking down GlcNAc, maintaining cell wall structure, and causing disease in the fungus Aspergillus fumigatus.

Contribution

The study identifies RonA as a key regulator of GlcNAc catabolism and cell wall integrity in A. fumigatus, offering new insights for antifungal drug development.

Findings

ΔronA mutants show severe growth defects, impaired cell wall integrity, and reduced virulence in a Galleria mellonella model.

RonA regulates GlcNAc catabolism and conidial cell wall architecture, affecting host-pathogen interactions.

ΔronA conidia exhibit increased surface protein exposure and reduced melanin, leading to enhanced immune clearance.

Abstract

Aspergillus fumigatus, a saprophytic mold, demonstrates metabolic versatility by utilizing diverse carbon sources to sustain its growth and pathogenic potential. While N-acetylglucosamine (GlcNAc), an ubiquitous amino sugar, serves as a vital nutrient, its catabolic pathway in A. fumigatus remains unexplored. Here, we identified core components of this pathway, including GlcNAc-6-phosphate deacetylase (DacA), glucosamine-6-phosphate deaminase (NagA), and the transcription factor RonA. The expressions of dacA, nagA, and ronA were strongly induced when GlcNAc was the sole carbon source. Both ΔdacA and ΔnagA mutants exhibited abolished growth under GlcNAc condition, whereas the ΔronA mutant exhibited pleiotropic defects, including severe growth defects, impaired polarity, delayed development, reduced cell wall integrity, and decreased virulence in a Galleria mellonella infection model. The deletion of ronA resulted in enhanced immune clearance and exacerbated inflammatory responses. Conidial cell wall analysis revealed that ΔronA conidia displayed aberrant cell wall architecture, primarily characterized by increased surface protein exposure and significantly reduced melanin. Collectively, our findings highlight RonA’s critical role in GlcNAc catabolism, conidial cell wall integrity, and the pathogenesis of A. fumigatus, providing novel insights into antifungal drug development.

Aspergillus fumigatus is a major human fungal pathogen known for its ability to cause a wide range of diseases, primarily due to its exceptional adaptability to diverse environments. This study identifies DacA and NagA as key enzymes in GlcNAc catabolism, while the transcription factor RonA is essential for growth, sporulation, and cell wall stress response on GlcNAc. Beyond regulating GlcNAc catabolism, RonA was found to play a pivotal role in modifying the conidial cell wall structure, influencing host-pathogen interactions, including immune modulation and pathogenicity. These findings highlight RonA as a potential therapeutic target for treating A. fumigatus infections.

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