title: Characterization of two β-decarboxylating dehydrogenases from Sulfolobus acidocaldarius.
abstract: Sulfolobus acidocaldarius, a hyperthermoacidophilic archaeon, possesses two β-decarboxylating dehydrogenase genes, saci_0600 and saci_2375, in its genome, which suggests that it uses these enzymes for three similar reactions in lysine biosynthesis through 2-aminoadipate, leucine biosynthesis, and the tricarboxylic acid cycle. To elucidate their roles, these two genes were expressed in Escherichia coli in the present study and their gene products were characterized. Saci_0600 recognized 3-isopropylmalate as a substrate, but exhibited slight and no activity for homoisocitrate and isocitrate, respectively. Saci_2375 exhibited distinct and similar activities for isocitrate and homoisocitrate, but no detectable activity for 3-isopropylmalate. These results suggest that Saci_0600 is a 3-isopropylmalate dehydrogenase for leucine biosynthesis and Saci_2375 is a dual function enzyme serving as isocitrate-homoisocitrate dehydrogenase. The crystal structure of Saci_0600 was determined as a closed-form complex that binds 3-isopropylmalate and Mg2+, thereby revealing the structural basis for the extreme thermostability and novel-type recognition of the 3-isopropyl moiety of the substrate.
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors: Kento
authors: K
authors: Takahashi
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors: Fumika
authors: F
authors: Nakanishi
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors: Takeo
authors: T
authors: Tomita
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors: Nagisa
authors: N
authors: Akiyama
authors: Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.|Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany.
authors: Kerstin
authors: K
authors: Lassak
authors: Max Planck Institute for Terrestrial Microbiology, Marburg, Germany.|Molecular Biology of Archaea, Institute of Biology II, University of Freiburg, Schaenzlestr. 1, 79104, Freiburg, Germany.
authors: Sonja-Verena
authors: SV
authors: Albers
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
authors: Tomohisa
authors: T
authors: Kuzuyama
authors: Biotechnology Research Center, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan. umanis@mail.ecc.u-tokyo.ac.jp.
authors: Makoto
authors: M
authors: Nishiyama
mesh_terms: D050539:3-Isopropylmalate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D007523:Isocitrates / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism; D008293:Malates / Q000378:metabolism; D011485:Protein Binding; D016945:Sulfolobus acidocaldarius / Q000201:enzymology* / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D007523:Isocitrates; D008293:Malates; C025313:beta-isopropylmalate; C034219:isocitric acid; D007521:Isocitrate Dehydrogenase; D050539:3-Isopropylmalate Dehydrogenase; D008274:Magnesium
keywords: 3-Isopropylmalate dehydrogenase; Crystal structure; Homoisocitrate dehydrogenase; Isocitrate dehydrogenase; Sulfolobus acidocaldarius; β-Decarboxylating dehydrogenase