A Novel Membrane-bound Glutathione S-Transferase Functions in the Stationary Phase of the Yeast Saccharomyces cerevisiae

Abstract

The glutathione S-transferases (GSTs) represent a significant group of detoxification enzymes that play an important role in drug resistance in all eukaryotic species. In this paper we report an identification and characterization of the two Saccharomyces cerevisiae genes, GTT1 and GTT2 (glutathione transferase 1 and 2), coding for functional GST enzymes. Despite only limited similarity with GSTs from other organisms (ϳ50%), recombinant Gtt1p and Gtt2p exhibit GST activity with 1-chloro-2,4-dinitrobenzene as a substrate. Both Gtt1p and Gtt2p are able to form homodimers, as determined by two hybrid assay. Subcellular fractionation demonstrated that Gtt1p associates with the endoplasmic reticulum. Expression of GTT1 is induced after diauxic shift and remains high throughout the stationary phase. Strains deleted for GTT1 and/or GTT2 are viable but exhibit increased sensitivity to heat shock in stationary phase and limited ability to grow at 39°C.

The crystal structure of the nitrogen regulation fragment of the yeast prion protein Ure2p

“…1), as suspected from the sequence similarity between these proteins (9,(32)(33)(34). However, it should be noted that no GST activity has been observed in Ure2p (9,32). The Ure2p(97-354) monomer has two domains and dimensions of approximately 57 Å ϫ 55 Å ϫ 36 Å.…”

A glutathione S-transferase from Proteus mirabilis involved in heavy metal resistance and its potential application in removal of Hg2+

“…In our present study, a novel Gst Pm -4 of P. mirabilis, was identified and characterized to be involved in heavy metal resistance. Although Gst Pm -4 possesses no cysteine, it is able to conjugate the model substrates CDNB and GSH, which means it belongs to the GST superfamily [30,31]. Considering the fact that it is generally accepted that proteins with >40% sequence identity belong to the same class, Gst Pm -4 resembling a new branch GST (IsoJ) from Rhodococcus AD45 was confirmed that it belonged to a new class of GST [2].…”

The yeast prion protein Ure2: Structure, function and folding

“…In contrast, GSTs use a conserved tyrosine, serine or cysteine residue to interact with the thiol group of GSH, thus increasing the reactivity of GSH, typically via a sequential mechanism [51][52][53]. In S. cerevisiae, the two GSTs that have been identified show activity towards CDNB, but do not possess peroxidase activity [54]. On the other hand, the two glutaredoxins are active towards both CDNB and hydroperoxides [55] and the three phospholipid hydroperoxide glutathione peroxidases show activity towards both lipid and non-lipid hydroperoxides [56].…”

“…3). However, Ure2 does not show a detectable level of GST activity with typical substrates, such as CDNB [27,29,54,60]. Recent studies have found that deletion of the URE2 gene increases the sensitivity of S. cerevisiae cells to heavy metals and cellular oxidants, such as hydrogen peroxide [60][61][62]; and a Ure2 homologue from Aspergillus nidulans, while lacking the nitrogen metabolite repression activity of Ure2, also contributes to heavy metal and xenobiotic resistance [63].…”