Structure of the monomeric isocitrate dehydrogenase: evidence of a protein monomerization by a domain duplication.
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.
Yasutake
Yoshiaki
Y
Division of Biological Sciences, Graduate School of Science, Hokkaido University, Kita-10, Nishi-8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
Watanabe
Seiya
S
Yao
Min
M
Takada
Yasuhiro
Y
Fukunaga
Noriyuki
N
Tanaka
Isao
I
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
D008345:Manganese; D009249:NADP; D007521:Isocitrate Dehydrogenase