title: Ancestral residues stabilizing 3-isopropylmalate dehydrogenase of an extreme thermophile: experimental evidence supporting the thermophilic common ancestor hypothesis.
abstract: Ancestral amino acid residues were inferred for 3-isopropylmalate dehydrogenase (IPMDH), and were introduced into the enzyme of an extreme thermophile, Sulfolobus sp. strain 7. The thermostability of the mutant enzymes was compared with that of the wild type enzyme. At least five of the seven mutants tested showed higher thermal stability than the wild type IPMDH. The results are compatible with the hyperthermophilic universal ancestor hypothesis. The results also provide a new method for designing thermostable enzymes. The method only relies on the first dimensional structures of homologous enzymes that can be obtained from genetic databases.
authors.affiliation: Department of Molecular Biology, Tokyo University of Pharmacy and Life Science, Horinouchi, Hachioji, Tokyo 192-0392, Japan.
authors.forename: J
authors.initials: J
authors.lastname: Miyazaki
authors.forename: S
authors.initials: S
authors.lastname: Nakaya
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: M
authors.initials: M
authors.lastname: Tamakoshi
authors.forename: T
authors.initials: T
authors.lastname: Oshima
authors.forename: A
authors.initials: A
authors.lastname: Yamagishi
mesh_terms: D002942:Circular Dichroism; D004795:Enzyme Stability / Q000235:genetics / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D006358:Hot Temperature; D006836:Hydro-Lyases / Q000235:genetics* / Q000378:metabolism*; D007521:Isocitrate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D016296:Mutagenesis / Q000235:genetics*; D011489:Protein Denaturation; D016415:Sequence Alignment; D017385:Sequence Homology; D016944:Sulfolobus / Q000201:enzymology* / Q000235:genetics; D013824:Thermus / Q000201:enzymology* / Q000235:genetics
chemical_list: D007521:Isocitrate Dehydrogenase; D006836:Hydro-Lyases; C021455:3-isopropylmalate dehydratase