Comparison of human glutamate carboxypeptidases II and III reveals their divergent substrate specificities
Autor: | Jan Tykvart, Jiří Schimer, Klára Hlouchová, Petr Pachl, Václav Navrátil, Lubomír Rulíšek, Jan Konvalinka, Tibor András Rokob, Michal Navrátil |
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Rok vydání: | 2016 |
Předmět: |
0301 basic medicine
Glutamate Carboxypeptidase II medicine.medical_treatment Protein Data Bank (RCSB PDB) Carboxypeptidases Biochemistry Divalent Substrate Specificity 03 medical and health sciences 0302 clinical medicine Glutamates Catalytic Domain Hydrolase medicine Glutamate carboxypeptidase II Humans Molecular Biology chemistry.chemical_classification Protease Binding Sites biology Molecular Structure Cell Biology computer.file_format Protein Data Bank Carboxypeptidase 030104 developmental biology Enzyme chemistry 030220 oncology & carcinogenesis Antigens Surface biology.protein Thermodynamics computer |
Zdroj: | The FEBS journal. 283(13) |
ISSN: | 1742-4658 |
Popis: | UNLABELLED Glutamate 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 β-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 analysed 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. DATABASE The X-ray structure of GCPII Glu424Ala in complex with BCG has been deposited in the RCSB Protein Data Bank under accession code 5F09. |
Databáze: | OpenAIRE |
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