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UniProt functional annotation for P18956 | ||
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| UniProt code: P18956. |
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| Organism: | |
Escherichia coli (strain K12). |
| Taxonomy: | |
Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacterales; Enterobacteriaceae; Escherichia. |
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| Function: | |
Cleaves the gamma-glutamyl bond of periplasmic glutathione (gamma-Glu-Cys-Gly), glutathione conjugates, and other gamma-glutamyl compounds. The metabolism of glutathione releases free glutamate and the dipeptide cysteinyl-glycine, which is hydrolyzed to cysteine and glycine by dipeptidases; it may function in amino acid uptake/salvage, or possibly in peptidoglycan linkage. Catalyzes the hydrolysis and transpeptidation of many gamma-glutamyl compounds (including some D- gamma-glutamyl substrates), with a preference for basic and aromatic amino acids as acceptors (PubMed:2877974). The KM values for gamma- glutamyl acceptors are so high that it has been proposed transpeptidation is not the physiological role in E.coli (PubMed:2877974, PubMed:8104180). {ECO:0000269|PubMed:2877974, ECO:0000305|PubMed:8104180}. |
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| Catalytic activity: | |
Reaction=an alpha-amino acid + an N-terminal (5-L-glutamyl)-[peptide] = 5-L-glutamyl amino acid + N-terminal L-alpha-aminoacyl-[peptide]; Xref=Rhea:RHEA:23904, Rhea:RHEA-COMP:9780, Rhea:RHEA-COMP:9795, ChEBI:CHEBI:77644, ChEBI:CHEBI:78597, ChEBI:CHEBI:78599, ChEBI:CHEBI:78608; EC=2.3.2.2; Evidence={ECO:0000269|PubMed:1360205}; |
| Catalytic activity: | |
Reaction=glutathione + H2O = L-cysteinylglycine + L-glutamate; Xref=Rhea:RHEA:28807, ChEBI:CHEBI:15377, ChEBI:CHEBI:29985, ChEBI:CHEBI:57925, ChEBI:CHEBI:61694; EC=3.4.19.13; Evidence={ECO:0000305|PubMed:2877974}; |
| Catalytic activity: | |
Reaction=an S-substituted glutathione + H2O = an S-substituted L- cysteinylglycine + L-glutamate; Xref=Rhea:RHEA:59468, ChEBI:CHEBI:15377, ChEBI:CHEBI:29985, ChEBI:CHEBI:90779, ChEBI:CHEBI:143103; EC=3.4.19.13; Evidence={ECO:0000305|PubMed:2877974}; |
| Activity regulation: | |
Transferase and hydrolase activities are inhibited by L-Ala and L-Gln, and also by GGT affinity labeling reagents such as azaserine and 6-diazo-5-oxo-nor-leucine. {ECO:0000269|PubMed:2877974}. |
| Biophysicochemical properties: | |
Kinetic parameters: KM=35 uM for glutathione transfer to glycylglycine (gly-gly) {ECO:0000269|PubMed:2877974}; KM=35 uM for gamma-glutamyl-p-nitroanilide (gamma-GpNA) transfer to gly-gly {ECO:0000269|PubMed:2877974}; KM=29 uM for glutathione hydrolysis {ECO:0000269|PubMed:2877974}; KM=68 uM for gamma-GpNA hydrolysis {ECO:0000269|PubMed:2877974}; pH dependence: Optimum pH is 8.73 for transfer of p-nitroanilide from gamma-GpNA to gly-gly and 9.25 for hydrolysis of gamma-GpNA. {ECO:0000269|PubMed:2877974}; Temperature dependence: Optimum temperature is 50 degrees Celsius for both transferase and hydrolase activities. {ECO:0000269|PubMed:2877974}; |
| Pathway: | |
Sulfur metabolism; glutathione metabolism. |
| Subunit: | |
This enzyme consists of two polypeptide chains, which are synthesized in precursor form from a single polypeptide. {ECO:0000269|PubMed:1360205, ECO:0000269|PubMed:16618936, ECO:0000269|PubMed:17135273, ECO:0000269|PubMed:18555071, ECO:0000269|PubMed:2877974}. |
| Subcellular location: | |
Periplasm {ECO:0000269|PubMed:1360205, ECO:0000269|PubMed:2877974}. |
| Ptm: | |
Cleaved by autocatalysis into a large and a small subunit. {ECO:0000269|PubMed:1360205, ECO:0000269|PubMed:16618936, ECO:0000269|PubMed:17135273, ECO:0000269|PubMed:18555071, ECO:0000269|PubMed:2570061}. |
| Disruption phenotype: | |
Loss of growth using exogenous gamma-glutamyl peptides as amino acid sources. {ECO:0000269|PubMed:8104180}. |
| Similarity: | |
Belongs to the gamma-glutamyltransferase family. {ECO:0000305}. |
Annotations taken from UniProtKB at the EBI.