Characterization of two β-decarboxylating dehydrogenases from Sulfolobus acidocaldarius

详细信息    查看全文

• 作者：Kento Takahashi ; Fumika Nakanishi ; Takeo Tomita ; Nagisa Akiyama…
• 关键词：β ; Decarboxylating dehydrogenase ; 3 ; Isopropylmalate dehydrogenase ; Isocitrate dehydrogenase ; Homoisocitrate dehydrogenase ; Crystal structure ; Sulfolobus acidocaldarius
• 刊名：Extremophiles
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：20
• 期：6
• 页码：843-853
• 全文大小：1,438 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Microbiology
  Biotechnology
  Ecology
  
• 出版者：Springer Japan
• ISSN：1433-4909
• 卷排序：20

文摘

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.