title: Essential 110Cys in active site of membrane-associated prostaglandin E synthase-2.
abstract: The amino acid sequence of membrane-associated prostaglandin (PG) E synthase-2 (mPGE synthase-2), which has a broad specificity in its thiol requirement for a catalytic activity, has the consensus region from 104Leu to 120Leu found in glutaredoxin and of thioredoxin. The sequence of Cys-x-x-Cys in the consensus region is the active site for thioredoxin and mPGE synthase-2 also has this amino acid sequence (110Cys-x-x-113Cys). The mutation from 110Cys to Ser or the double mutation from 110Cys and 113Cys to Ser caused loss of PGE synthase activity, whereas the single mutation from 113Cys to Ser did not affect the enzyme activity. These results indicate that 110Cys, but not 113Cys, is the essential amino acid in the active site of mPGE synthase-2. 110Cys is an important amino acid in PGE synthase activity and plays the critical role as Cys at the same position in redoxin. Moreover, we found that the reduced form of lipoic acid (dihydrolipoic acid) serves as one of the natural activators of mPGE synthase-2 in the cells.
authors.affiliation: Division of Life Science, Graduate School of Integrated Science and Art, University of East Asia, 2-1 Ichinomiya-gakuencho, Shimonoseki, Yamaguchi 751-8503, Japan. watanabe@po.cc.toia-u.ac.jp
authors.forename: Kikuko
authors.initials: K
authors.lastname: Watanabe
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohkubo
authors.forename: Haruki
authors.initials: H
authors.lastname: Niwa
authors.forename: Naomi
authors.initials: N
authors.lastname: Tanikawa
authors.forename: Noriko
authors.initials: N
authors.lastname: Koda
authors.forename: Seiji
authors.initials: S
authors.lastname: Ito
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Ohmiya
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry*; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D054477:Glutaredoxins; D006801:Humans; D019746:Intramolecular Oxidoreductases / Q000737:chemistry*; D007700:Kinetics; D007930:Leucine / Q000737:chemistry; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010088:Oxidoreductases; D000071876:Prostaglandin-E Synthases; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry; D012694:Serine / Q000737:chemistry; D008063:Thioctic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D013879:Thioredoxins / Q000737:chemistry
chemical_list: D054477:Glutaredoxins; D011506:Proteins; D012694:Serine; D013879:Thioredoxins; D008063:Thioctic Acid; C015144:dihydrolipoic acid; D010088:Oxidoreductases; D019746:Intramolecular Oxidoreductases; D000071876:Prostaglandin-E Synthases; D007930:Leucine; D003545:Cysteine; D004229:Dithiothreitol