Arsenic toxicity and its mitigation in ectomycorrhizal fungus Hebeloma cylindrosporum through glutathione biosynthesis

• Published in: Chemosphere (Oxford) 2020-02, Vol.240, p.124914-124914, Article 124914
• Main Authors: Khullar, Shikha, Reddy, M. Sudhakara
• Format: Article
• Language: English
• Subjects: Antioxidants - metabolism; Arsenic; Arsenic - metabolism; Arsenic - toxicity; Ectomycorrhizal fungi; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene Expression Regulation, Fungal - drug effects; Genetic Complementation Test; Glutamate-Cysteine Ligase - genetics; Glutamate-Cysteine Ligase - metabolism; Glutathione; Glutathione - biosynthesis; Glutathione - metabolism; Glutathione Synthase - genetics; Glutathione Synthase - metabolism; Glutathione synthetase; Hebeloma - drug effects; Hebeloma - genetics; Hebeloma - metabolism; Hebeloma cylindrosporum; Inactivation, Metabolic; Mutation; Mycorrhizae - drug effects; Mycorrhizae - genetics; Mycorrhizae - metabolism; Saccharomyces cerevisiae - metabolism; Soil Pollutants - metabolism; Soil Pollutants - toxicity; γ-glutamylcysteine synthetase
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.124914

Arsenic (As) contamination is one of the most daunting environmental problem bothering the whole world. Exploring a suitable bioremediation technique is an urgent need of the hour. The present study focusses on scrutinizing the ectomycorrhizal (ECM) fungus for its potential role in As detoxification and understanding the molecular mechanisms responsible for its tolerance. When exposed to increasing concentrations of external As, the ECM fungus H. cylindrosporum accumulated the metalloid intracellularly, inducing the glutathione biosynthesis pathway. The genes coding for GSH biosynthesis enzymes, γ-glutamylcysteine synthetase (Hcγ-GCS) and glutathione synthetase (HcGS) were highly regulated by As stress. Arsenic coordinately upregulated the expression of both Hcγ-GCS and HcGS genes, thus resulting in increased Hcγ-GCS and HcGS protein expressions and enzyme activities, with substantial increase in intracellular GSH. Functional complementation of the two genes (Hcγ-GCS and HcGS) in their respective yeast mutants (gsh1Δ and gsh2Δ) further validated the role of both enzymes in mitigating As toxicity. These findings clearly highlight the potential importance of GSH antioxidant defense system in regulating the As induced responses and its detoxification in ECM fungus H. cylindrosporum. [Display omitted] •Glutathione biosynthesizing genes, Hcγ-GCS and HcGS were characterized in H. cylindrosporum.•Enhanced accumulation and glutathione content were observed due to As exposure.•Yeast mutants rescued the As sensitivity due to cloning of Hcγ-GCS and HcGS.•mRNA accumulation of Hcγ-GCS and HcGS increased significantly due to As exposure.•Glutathione play an important role in As detoxification in ECM fungus H. cylindrosporum.