Mammalian class Sigma glutathione S-transferases: catalytic properties and tissue-specific expression of human and rat GSH- dependent prostaglandin D-2 synthases


Jowsey, IR; Thomson, AM; Flanagan, JU; Murdock, PR; Moore, GBT; Meyer, DJ; Murphy, GJ; Smith, SA; Hayes, JD; (2001) Mammalian class Sigma glutathione S-transferases: catalytic properties and tissue-specific expression of human and rat GSH- dependent prostaglandin D-2 synthases. The Biochemical journal, 359 (Pt 3). pp. 507-16. ISSN 0264-6021

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Abstract

GSH-dependent prostaglandin D(2) synthase (PGDS) enzymes represent the only vertebrate members of class Sigma glutathione S-transferases (GSTs) identified to date. Complementary DNA clones encoding the orthologous human and rat GSH-dependent PGDS (hPGDS and rPGDS, respectively) have been expressed in Escherichia coli, and the recombinant proteins isolated by affinity chromatography. The purified enzymes were both shown to catalyse specifically the isomerization of prostaglandin (PG) H(2) to PGD(2). Each transferase also exhibited GSH-conjugating and GSH-peroxidase activities. The ability of hPGDS to catalyse the conjugation of aryl halides and isothiocyanates with GSH was found to be less than that of the rat enzyme. Whilst there is no difference between the enzymes with respect to their K(m) values for 1-chloro-2,4-dinitrobenzene, marked differences were found to exist with respect to their K(m) for GSH (8 mM versus 0.3 mM for hPGDS and rPGDS, respectively). Using molecular modelling techniques, amino acid substitutions have been identified in the N-terminal domain of these enzymes that lie outside the proposed GSH-binding site, which may explain these catalytic differences. The tissue-specific expression of PGDS also varies significantly between human and rat; amongst the tissues examined, variation in expression between the two species was most apparent in spleen and bone marrow. Differences in catalytic properties and tissue-specific expression of hPGDS and rPGDS appears to reflect distinct physiological roles for class Sigma GST between species. The evolution of divergent functions for the hPGDS and rPGDS is discussed in the context of the orthologous enzyme from chicken.

Item Type: Article
Keywords: detoxification, gene expression, prostaglandin synthesis, D synthetase, transcriptional regulation, crystal-structure, ppar-gamma, mast-cells, receptor, sequence, genes, differentiation, localization, Amino Acid Sequence, Animal, Catalysis, Glutathione Transferase, classification, genetics, metabolism, Human, Intramolecular Oxidoreductases, chemistry, genetics, metabolism, Isoenzymes, metabolism, Models, Molecular, Molecular Sequence Data, Organ Specificity, Protein Conformation, Protein Structure, Tertiary, Rats, Rats, Wistar, Recombinant Proteins, metabolism, Sequence Alignment, Support, Non-U.S. Gov't
Faculty and Department: Faculty of Infectious and Tropical Diseases > Dept of Pathogen Molecular Biology
PubMed ID: 11672424
Web of Science ID: 172243600004
URI: http://researchonline.lshtm.ac.uk/id/eprint/17281

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