5f09
Structure of inactive GCPII mutant in complex with beta-citryl glutamateStructure of inactive GCPII mutant in complex with beta-citryl glutamate
Structural highlights
FunctionFOLH1_HUMAN Has both folate hydrolase and N-acetylated-alpha-linked-acidic dipeptidase (NAALADase) activity. Has a preference for tri-alpha-glutamate peptides. In the intestine, required for the uptake of folate. In the brain, modulates excitatory neurotransmission through the hydrolysis of the neuropeptide, N-aceylaspartylglutamate (NAAG), thereby releasing glutamate. Isoform PSM-4 and isoform PSM-5 would appear to be physiologically irrelevant. Involved in prostate tumor progression. Also exhibits a dipeptidyl-peptidase IV type activity. In vitro, cleaves Gly-Pro-AMC. Publication Abstract from PubMedGlutamate carboxypeptidase III (GCPIII) is best known as a homologue of glutamate carboxypeptidase II [GCPII; also known as prostate-specific membrane antigen (PSMA)], a protease involved in neurological disorders and overexpressed in a number of solid cancers. However, mouse GCPIII was recently shown to cleave beta-citrylglutamate (BCG), suggesting that these two closely related enzymes have distinct functions. To develop a tool to dissect, evaluate and quantify the activities of human GCPII and GCPIII, we analyzed the catalytic efficiencies of these enzymes towards three physiological substrates. We observed a high efficiency of BCG cleavage by GCPIII but not GCPII. We also identified a strong modulation of GCPIII enzymatic activity by divalent cations, while we did not observe this effect for GCPII. Additionally, we used X-ray crystallography and computational modelling (quantum and molecular mechanical calculations) to describe the mechanism of BCG binding to the active sites of GCPII and GCPIII, respectively. Finally, we took advantage of the substantial differences in the enzymatic efficiencies of GCPII and GCPIII towards their substrates, using enzymatic assays for specific detection of these proteins in human tissues. Our findings suggest that GCPIII may not act merely as a complementary enzyme to GCPII, and it more likely possesses a specific physiological function related to BCG metabolism in the human body. This article is protected by copyright. All rights reserved. Comparison of human glutamate carboxypeptidases II and III reveals their divergent substrate specificities.,Navratil M, Tykvart J, Schimer J, Pachl P, Navratil V, Rokob TA, Hlouchova K, Rulisek L, Konvalinka J FEBS J. 2016 May 21. doi: 10.1111/febs.13761. PMID:27208881[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
|
| ||||||||||||||||||