ジャーナル: J Mol Biol / 年: 2019 タイトル: Structural and Mechanistic Insights into Caffeine Degradation by the Bacterial N-Demethylase Complex. 著者: Jun Hoe Kim / Bong Heon Kim / Shelby Brooks / Seung Yeon Kang / Ryan M Summers / Hyun Kyu Song / 要旨: Caffeine, found in many foods, beverages, and pharmaceuticals, is the most used chemical compound for mental alertness. It is originally a natural product of plants and exists widely in environmental ...Caffeine, found in many foods, beverages, and pharmaceuticals, is the most used chemical compound for mental alertness. It is originally a natural product of plants and exists widely in environmental soil. Some bacteria, such as Pseudomonas putida CBB5, utilize caffeine as a sole carbon and nitrogen source by degrading it through sequential N-demethylation catalyzed by five enzymes (NdmA, NdmB, NdmC, NdmD, and NdmE). The environmentally friendly enzymatic reaction products, methylxanthines, are high-value biochemicals that are used in the pharmaceutical and cosmetic industries. However, the structures and biochemical properties of bacterial N-demethylases remain largely unknown. Here, we report the structures of NdmA and NdmB, the initial N- and N-specific demethylases, respectively. Reverse-oriented substrate bindings were observed in the substrate-complexed structures, offering methyl position specificity for proper N-demethylation. For efficient sequential degradation of caffeine, these enzymes form a unique heterocomplex with 3:3 stoichiometry, which was confirmed by enzymatic assays, fluorescent labeling, and small-angle x-ray scattering. The binary structure of NdmA with the ferredoxin domain of NdmD, which is the first structural information for the plant-type ferredoxin domain in a complex state, was also determined to better understand electron transport during N-demethylation. These findings broaden our understanding of the caffeine degradation mechanism by bacterial enzymes and will enable their use for industrial applications.
設備名称: Photon Factory (PF), High Energy Accelerator Research Organization (KEK) BL-10C 地域: Tsukuba / 国: Japan / 線源: X-ray synchrotron / 波長: 0.15 Å / スペクトロメータ・検出器間距離: 3 mm
検出器
名称: Pilatus3 2M / Pixsize x: 0.172 mm
スキャン
タイトル: Pseudomonas putida CBB5 NdmB hexamer / 測定日: 2018年5月21日 / 保管温度: 4 °C / セル温度: 18 °C / 照射時間: 10 sec. / フレーム数: 36 / 単位: 1/A /