Functional analysis of a fungal dioxygenase responsible for 4-pyrone formation

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K06720
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 47050:Environmental and natural pharmaceutical resources-related
• Research Institution: Musashino University
• Principal Investigator: Hashimoto Makoto 武蔵野大学, 薬学部, 講師 (80552893)
• Project Period (FY): 2018-04-01 – 2022-03-31
• Keywords: ポリケタイド / 生合成 / 糸状菌 / ジオキシゲナーゼ

Outline of Final Research Achievements

Himeic acid is produced by the filamentous fungus Aspergillus japonicus MF275. We have found a dioxygenase that is expected to catalyze the reaction of ring-expanding tetramic acid, which is a presumed biosynthesis intermediate, to 4-pyrone. In this study, we tried to analyze the function of this enzyme and perform the prediction of protein-ligand docking on homology model.
Preparation of a tetramate, which is putative intermediate, was unsuccessful, probably due to poor enzyme expression of himA (PKS-NRPS) or himH (dehydrogenase) in yeast transformant. We also attempted a computational approach for important amino acid residues by modeling analysis. In HimG modeling analysis, the presence of basic amino acids (R83, K87, R241) that interact with 2-oxoglutaric acid is important for the reaction mechanism of 2-oxoglutaric acid-dependent dioxygenase. An putative tetramate intermediate was estimated to interact with H148 of HimG.

Free Research Field

天然物化学

Academic Significance and Societal Importance of the Research Achievements

テトラミン酸から4-ピロンの環拡張反応は、多くの二次代謝産物の生合成経路に含まれている。この反応の多くは、モノオキシゲナーゼやシトクロムP450のような酸化酵素が関与している。もし本反応がジオキシゲナーゼで代用できれば、モノオキシゲナーゼのような機能解析を行うための発現伴う困難が軽減される。本研究でジオキシゲナーゼによる活性の評価系が解決でき、モデリング研究などによる予測ができれば、微生物酵素を利用した4-ピロン化合物を生産させる生物合成システムの構築に展開が期待できる。