University of the Ryukyus · Faculty of Agriculture · 准教授

Research keywordsmimosine metabolism・mimosine degradation・mimosinase・cysteine synthase・Leucaena leucocephala・Mimosa pudica・plant sulfur metabolism

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• Isolation and characterization of mimosine degrading enzyme from Arthrobacter sp. Ryudai-S12022 · Oogai, S; Fukuta, M; Inafuku, M; Oku, H
• Molecular cloning of putative chloroplastic cysteine synthase in Leucaena leucocephala.2020 · Cysteine biosynthesis is directed by the successive commitments of serine acetyltransferase, and O-acetylserine (thiol) lyase (OASTL) compounds, which subsequently frame the decameric cysteine synthase complex. The isoforms of OASTL are found in three compartments of the cell: the cytosol, plastid, and mitochondria. In this investigation, we first isolated putative chloroplastic OASTL (Ch-OASTL) from Leucaena leucocephala, and the Ch-OASTL was then expressed in BL21-competent Escherichia coli. The putative Ch-OASTL cDNA clone had 1,543 base pairs with 391 amino acids in its open reading frame and a molecular weight of 41.54 kDa. The purified protein product exhibited cysteine synthesis ability, but not mimosine synthesis activity. However, they both make the common α-aminoacrylate intermediate in their first half reaction scheme with the conventional substrate O-acetyl serine (OAS). Hence, we considered putative Ch-OASTL a cysteine-specific enzyme. Kinetic studies demonstrated that the optimum pH for cysteine synthesis was 7.0, and the optimum temperature was 40 °C. In the cysteine synthesis assay, the Km and kcat values were 838 ± 26 µM and 72.83 s-1 for OAS, respectively, and 60 ± 2 µM and 2.43 s-1 for Na2S, respectively. We can infer that putative Ch-OASTL regulatory role is considered a sensor for sulfur constraint conditions, and it acts as a forerunner of various metabolic compound molecules.
• Molecular characterization of mimosinase and cystathionine β-lyase in the Mimosoideae subfamily member Mimosa pudica.2019 · Oogai S, Fukuta M, Watanabe K, Inafuku M, Oku H
• Molecular characterization of cytosolic cysteine synthase in Mimosa pudica.2018 · Rashid MH, Iwasaki H, Oogai S, Fukuta M, Parveen S, Hossain MA, Anai T, Oku H

• 亜熱帯マメ科植物ギンネム及び周辺生物が持つミモシン代謝酵素遺伝子の起源の研究2004 · 萌芽研究
• 非タンパク質性アミノ酸ミモシン代謝酵素遺伝子1900 · ■■■
• 亜熱帯植物の環境耐性遺伝子1900 · ■■■

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