title: Structure of the monomeric isocitrate dehydrogenase: evidence of a protein monomerization by a domain duplication.
abstract: NADP(+)-dependent isocitrate dehydrogenase is a member of the beta-decarboxylating dehydrogenase family and catalyzes the oxidative decarboxylation reaction from 2R,3S-isocitrate to yield 2-oxoglutarate and CO(2) in the Krebs cycle. Although most prokaryotic NADP(+)-dependent isocitrate dehydrogenases (IDHs) are homodimeric enzymes, the monomeric IDH with a molecular weight of 80-100 kDa has been found in a few species of bacteria. The 1.95 A crystal structure of the monomeric IDH revealed that it consists of two distinct domains, and its folding topology is related to the dimeric IDH. The structure of the large domain repeats a motif observed in the dimeric IDH. Such a fusional structure by domain duplication enables a single polypeptide chain to form a structure at the catalytic site that is homologous to the dimeric IDH, the catalytic site of which is located at the interface of two identical subunits.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-10, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yasutake
authors.forename: Seiya
authors.initials: S
authors.lastname: Watanabe
authors.forename: Min
authors.initials: M
authors.lastname: Yao
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takada
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Fukunaga
authors.forename: Isao
authors.initials: I
authors.lastname: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D016948:Azotobacter vinelandii / Q000201:enzymology; D002384:Catalysis; D019281:Dimerization; D007521:Isocitrate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism; D008345:Manganese / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D008345:Manganese; D009249:NADP; D007521:Isocitrate Dehydrogenase