Characterization of glutathione S-transferase enzymes in Dictyostelium discoideum suggests a functional role for the GSTA2 isozyme in cell proliferation and development

We extend our previous characterization of Dictyostelium discoideum glutathione S-transferase enzymes that are expressed in the eukaryotic model organism

Mamatha Garige; Eric Walters


Scholarcy highlights

  • Glutathione S-transferases are phase II biotransformation enzymes that play important roles in cellular metabolism and detoxification
  • We extend our previous characterization of GST enzymes in D. discoideum through biochemical and molecular genetic analyses of two DdGSTA isozymes
  • The collective decrease in gstA1-A5 transcripts in starved cells correlated with reduced GST enzymatic activity, as a 60% reduction of GST activity was found in starved cells as compared to vegetative cells
  • In this study we identified five D. discoideum alpha class GST transcripts in unicellular, vegetative amoebae, whose expression was altered in response to starvation that induces multicellular development
  • Mass spectrometric analysis of the expressed GST enzymes that were isolated from axenically growing D. discoideum cells by GSH affinity chromatography revealed three of the five putative GST alpha isozymes, DdGSTA1, DdGSTA2, and DdGSTA3
  • The absence of DdGSTA4 and DdGSTA5 isozymes may be the consequence of reduced expression levels of each isozyme in vegetative cells, and/ or stereochemical conformation(s) that inhibit their isolation with GSH binding
  • Recent findings that the DdGST4 isozyme functions as a DIF-1 binding protein to regulate the sizes of cell aggregates and fruiting bodies in D. discoideum provides further evidence to explore non-enzymatic roles of discoideum glutathione S-transferase. Amid the changes in GST expression and activity, the role of GSH should be considered, as modulation of GSH affects stage-specific development via the YakA signaling pathway, and is a substrate for GSTs

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