Study on the glutathione metabolism of the filamentous fungus Aspergillus nidulans

Abstract

Yeast protein sequence-based homology search for glutathione (GSH) metabolic enzymes and GSH transporters demonstrated that Aspergillus nidulans has a robust GSH uptake and metabolic system with several paralogous genes. In wet laboratory experiments, two key genes of GSH metabolism, gcsA, and glrA, encoding γ-L-glutamyl-L-cysteine synthetase and glutathione reductase, respectively, were deleted. The gene gcsA was essential, and the ΔgcsA mutant required GSH supplementation at considerably higher concentration than the Saccharomyces cerevisiae gsh1 mutant (8-10 mmol l −1 vs. 0.5 μmol l −1 ). In addition to some functions known previously, both genes were important in the germination of conidiospores, and both gene deletion strains required the addition of extra GSH to reach wild-type germination rates in liquid cultures. Nevertheless, the supplementation of cultures with 10 mmol l −1 GSH was toxic for the control and ΔglrA strains especially during vegetative growth, which should be considered in future development of high GSHproducer fungal strains. Importantly, the ΔglrA strain was characterized by increased sensitivity toward a wide spectrum of osmotic, cell wall integrity and antimycotic stress conditions in addition to previously reported temperature and oxidative stress sensitivities. These novel phenotypes underline the distinguished functions of GSH and GSH metabolic enzymes in the stress responses of fungi.

Velvet domain protein VosA represses the zinc cluster transcription factor SclB regulatory network for Aspergillus nidulans asexual development, oxidative stress response and secondary metabolism

“…The sclB OE strain stressed with H 2 O 2 shows an increased trxR upregulation compared to wildtype ( Fig 10B ). glrA encodes the glutathione reductase [ 92 , 93 ], which regulation was not dependent on the presence of sclB ( S7 Fig ). The catA gene, encoding the spore-specific catalase A, is upregulated in wildtype but not induced in Δ sclB in presence of H 2 O 2 ( Fig 10B ).…”

Transcriptome-Based Modeling Reveals that Oxidative Stress Induces Modulation of the AtfA-Dependent Signaling Networks inAspergillus nidulans

“…This gene group includes genes encoding known and likely antioxidant enzymes ( Aspergillus Genome Database; [47]).…”

Genome-wide analysis and prediction of genes involved in the biosynthesis of polysaccharides and bioactive secondary metabolites in high-temperature-tolerant wild Flammulina filiformis

“…In addition, the genes involved in glutathione metabolism were significantly enriched in DK of the wild strain Liu 355 compared to the cultivar strain CGMCC 5.642. A study on the glutathione metabolism in the filamentous fungus Aspergillus nidulans indicated that glutathione itself and glutathione metabolic enzymes play crucial roles in the germination of conidiospores and markedly contribute to the general stress tolerance of the fungus [52]. The high expression of genes related to glutathione metabolism in the wild strain of F. filiformis implied that the strain probably had strong environmental adaptation and it would be a potential better breeding resource.…”