Fungi that can reduce elemental sulfur to sulfide are widely distributed, but the mechanism and physiological significance of the reaction have been poorly characterized. Here, we purified elemental sulfur-reductase (SR) and cloned its gene from the elemental sulfur-reducing fungus Fusarium oxysporum. We found that NADPH-glutathione reductase (GR) reduces elemental sulfur via glutathione as an intermediate. A loss-of-function mutant of the SR/GR gene generated less sulfide from elemental sulfur than the wild-type strain. Its growth was hypersensitive to elemental sulfur, and it accumulated higher levels of oxidized glutathione, indicating that the GR/glutathione system confers tolerance to cytotoxic elemental sulfur by reducing it to less harmful sulfide. The SR/GR reduced polysulfide as efficiently as elemental sulfur, which implies that soluble polysulfide shuttles reducing equivalents to exocellular insoluble elemental sulfur and generates sulfide. The ubiquitous distribution of the GR/glutathione system together with our findings that GR-deficient mutants derived from Saccharomyces cerevisiae and Aspergillus nidulans reduced less sulfur and that their growth was hypersensitive to elemental sulfur indicated a wide distribution of the system among fungi. These results indicate a novel biological function of the GR/glutathione system in elemental sulfur reduction, which is distinguishable from bacterial and archaeal mechanisms of glutathione- independent sulfur reduction.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|