title: Characterization of NADP(+)-dependent isocitrate dehydrogenase isozymes from a psychrophilic bacterium, Colwellia psychrerythraea strain 34H.
abstract: NADP(+)-dependent isocitrate dehydrogenase (IDH) isozymes of a psychrophilic bacterium, Colwellia psychrerythraea strain 34H, were characterized. The coexistence of monomeric and homodimeric IDHs in this bacterium was confirmed by Western blot analysis, the genes encoding two monomeric (IDH-IIa and IDH-IIb) and one dimeric (IDH-I) IDHs were cloned and overexpressed in Escherichia coli, and the three IDH proteins were purified. Both of the purified IDH-IIa and IDH-IIb were found to be cold-adapted enzymes while the purified IDH-I showed mesophilic properties. However, the specific activities of IDH-IIa and IDH-IIb were lower even at low temperatures than that of IDH-I. Therefore, IDH-I was suggested to be important for the growth of this bacterium. The results of colony formation of E. coli transformants carrying the respective IDH genes and IDH activities in their crude extracts indicated that the expression of the IDH-IIa gene is cold-inducible in the E. coli cells.
authors.affiliation: a Biosystems Science Course, Graduate School of Life Science , Hokkaido University , Sapporo , Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Suzuki
authors.affiliation: b Faculty of Science, Department of Biological Sciences , Hokkaido University , Sapporo , Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takada
mesh_terms: D000222:Adaptation, Physiological; D034241:Alteromonadaceae / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D002876:Chromosomes, Bacterial / Q000737:chemistry; D003001:Cloning, Molecular; D003080:Cold Temperature; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D055503:Protein Multimerization; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D007521:Isocitrate Dehydrogenase; C039355:isocitrate dehydrogenase (NADP+)
keywords: Colwellia psychrerythraea strain 34H; cold-adapted enzyme; isocitrate dehydrogenase; isozymes