C-terminal, alpha helical domain of Escherichia coli YfcG Glutathione S-transferases and related uncharacterized proteins
Glutathione S-transferase (GST) C-terminal domain family, YfcG-like subfamily; composed of the Escherichia coli YfcG and related proteins. GSTs are cytosolic dimeric proteins involved in cellular detoxification by catalyzing the conjugation of glutathione (GSH) with a wide range of endogenous and xenobiotic alkylating agents, including carcinogens, therapeutic drugs, environmental toxins and products of oxidative stress. GSTs also show GSH peroxidase activity and are involved in the synthesis of prostaglandins and leukotrienes. The GST active site is located in a cleft between the N- and C-terminal domains. GSH binds to the N-terminal domain while the hydrophobic substrate occupies a pocket in the C-terminal domain. YfcG is one of nine GST homologs in Escherichia coli. It is expressed predominantly during the late stationary phase where the predominant form of GSH is glutathionylspermidine (GspSH), suggesting that YfcG might interact with GspSH. It has very low or no GSH transferase or peroxidase activity, but displays a unique disulfide bond reductase activity that is comparable to thioredoxins (TRXs) and glutaredoxins (GRXs). However, unlike TRXs and GRXs, YfcG does not contain a redox active cysteine residue and may use a bound thiol disulfide couple such as 2GSH/GSSG for activity. The crystal structure of YcfG reveals a bound GSSG molecule in its active site. The actual physiological substrates for YfcG are yet to be identified.
Comment:The prototypical member of this subfamily, Escherichia coli YfcG, is a unique GSH-dependent disulfide bond oxidoreductase that may use a bound thiol disulfide couple like 2GSH/GSSG for activity.
Structure:3GX0; Escherichia coli YfcG, an oxidoreductase, binds oxidized glutathione disulfide GSSG; contacts at 4A.
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