Identification of Glutathione S-Transferase (GST) Genes from a Dark Septate Endophytic Fungus (Exophiala pisciphila) and Their Expression Patterns under Varied Metals Stress

Abstract

Glutathione S-transferases (GSTs) compose a family of multifunctional enzymes that play important roles in the detoxification of xenobiotics and the oxidative stress response. In the present study, twenty four GST genes from the transcriptome of a metal-tolerant dark septate endophyte (DSE), Exophiala pisciphila, were identified based on sequence homology, and their responses to various heavy metal exposures were also analyzed. Phylogenetic analysis showed that the 24 GST genes from E. pisciphila (EpGSTs) were divided into eight distinct classes, including seven cytosolic classes and one mitochondrial metaxin 1-like class. Moreover, the variable expression patterns of these EpGSTs were observed under different heavy metal stresses at their effective concentrations for inhibiting growth by 50% (EC50). Lead (Pb) exposure caused the up-regulation of all EpGSTs, while cadmium (Cd), copper (Cu) and zinc (Zn) treatments led to the significant up-regulation of most of the EpGSTs (p < 0.05 to p < 0.001). Furthermore, although heavy metal-specific differences in performance were observed under various heavy metals in Escherichia coli BL21 (DE3) transformed with EpGSTN-31, the over-expression of this gene was able to enhance the heavy metal tolerance of the host cells. These results indicate that E. Pisciphila harbored a diverse of GST genes and the up-regulated EpGSTs are closely related to the heavy metal tolerance of E. pisciphila. The study represents the first investigation of the GST family in E. pisciphila and provides a primary interpretation of heavy metal detoxification for E. pisciphila.

EpABC Genes in the Adaptive Responses of Exophiala pisciphila to Metal Stress: Functional Importance and Relation to Metal Tolerance

“…This situation suggests an alternative mechanistic explanation, that the accumulated toxic metal ions could form complexes with phytochelatins (PCs) or glutathione (GSH), e.g., PC-Cd or GSH-Cd/Pb complexes, and are then transported into the vacuoles of cells by numerous ABC transporters for final detoxification (28,32,(40)(41)(42)(43)(44), which was further confirmed by the subcellular location of the 3 EpABC proteins in the vacuole membrane. This was consistent with our previous findings that GSH synthetase genes and proteins in E. pisciphila were upregulated under Pb, Zn, and Cd stresses (45). Altogether, the data suggest that EpABC2.1 and EpABC3.1 conferred Pb, Zn, and Cd tolerance by compartmentalization of GSH-metal ions into vacuoles.…”

Melatonin Confers Heavy Metal Tolerance of a Dark Septate Endophyte (DSE) Exophiala Pisciphila Via Lowering Oxidative Stress and Heavy Metal Accumulation

“…3D). While Pb had no mitigating effect on melatonin production similar to that observed in rice [27], which indicated that E. pisciphila have distinct stress responses to the different type heavy metals [28]. The application of exogenous melatonin reduced OFR and MDA contents of E. pisciphila under Cd, Zn and Pb stresses (Fig.…”

An orphan protein of Fusarium graminearum modulates host immunity by mediating proteasomal degradation of TaSnRK1α

“…Osp24, TaSnRK1α, and TaFROG cDNA fragments were amplified and cloned into pGEX4T1 94 and pCold 95 for purification of Osp24-GST, TaSnRK1α-His, and TaFROG-S recombinant proteins 96 . To assay their interactions, equal amounts of Osp24-GST and TaSnRK1α-HIS fusion proteins were incubated at 4 °C for 2 h and mixed with glutathione or Ni-NTA resins (GenScript, China) for affinity purification 97 , 98 .…”