1k0a
From Proteopedia
Ure2p in Complex with S-hexylglutathione
Structural highlights
Function[URE2_YEAST] Plays an important role in nitrogen catabolite repression. Down-regulates the expression of many genes involved in nitrogen utilization by inhibiting the GATA transcriptional activators GLN3 and GAT1. Under good nitrogen conditions, binds to the phosphorylated forms of GLN3 and GAT1 and sequesters them in the cytoplasm, preventing transcription of genes expressed upon nitrogen limitation. Is also an atypical glutaredoxin without a catalytical cysteine residue. Has glutathione peroxidase and thiol:disulfide oxidoreductase activities in both native and fibrillar form. Also shows insulin disulfide reductase and dehydroascorbic acid reductase (DHAR) actvites.[1] [2] [3] [4] [5] [6] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe [URE3] phenotype in yeast Saccharomyces cerevisiae is due to an altered prion form of Ure2p, a protein involved in nitrogen catabolism. To understand possible conformational changes at the origin of prion propagation, we previously solved the crystal structure of the Ure2p functional region [Bousset et al. (2001) Structure 9, 39-46]. We showed the protein to have a fold similar to that of the beta class of glutathione S-transferases (GSTs). Here we report crystal structures of the Ure2p functional region (extending from residues 95-354) in complex with glutathione (GSH), the substrate of all GSTs, and two widely used GST inhibitors, namely, S-hexylglutathione and S-p-nitrobenzylglutathione. In a manner similar to what is observed in many GSTs, ligand binding is not accompanied by a significant change in the conformation of the protein. We identify one GSH and one hydrophobic electrophile binding site per monomer as observed in all other GSTs. The sulfur group of GSH, that conjugates electrophiles, is located near the amide group of Asn124, allowing a hydrogen bond to be formed. Biochemical data indicate that GSH binds to Ure2p with high affinity. Its binding affects Ure2p oligomerization but has no effect on the assembly of the protein into amyloid fibrils. Despite results indicating that Ure2p lacks GST activity, we propose that Ure2p is a member of the GST superfamily that may describe a novel GST class. Our data bring new insights into the function of the Ure2p active region. Crystal structures of the yeast prion Ure2p functional region in complex with glutathione and related compounds.,Bousset L, Belrhali H, Melki R, Morera S Biochemistry. 2001 Nov 13;40(45):13564-73. PMID:11695904[7] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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