Kagoshima University · Faculty of Agriculture · 教授

Research keywordsmicrobiology・微生物学・好塩性酵素・タンパク質構造・微生物群集・L-アラビノースイソメラーゼ・熱安定性

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• Nagaoka A., Yamagami F., Otsuka Y., Kashiki M., Kikuchi A., Osaki Y., Tsurumaru H., Tokunaga M., Ishibashi M. . A stress-tolerant, chaperone-like peptidylprolyl isomerase (PPIase) from Chromoh2026 · 記述言語： 日本語 出版者・発行元： Journal of Biotechnology Halophilic bacteria have evolved exceptionally high protein solubility to withstand aggregation in high-salt environments. Leveraging this trait, we isolated a chaperone-like peptidylprolyl isomerase (PPIase) from the moderately halophilic bacterium Chromohalobacter salexigens that remains soluble under heat, acid, and organic solvent stresses. We constructed Escherichia coli fusion expression vectors incorporating this PPIase and demonstrated enhanced intracellular solubility of two aggregation-prone L -arabinose isomerases that catalyze the production of the rare sugar D -tagatose: GSAI from Geobacillus stearothermophilus and THAI from Tetragenococcus halophilus. Introduction of a flexible linker (S2H6S2) between the fusion partner and target proteins improved solubility, enabling approximately 76% soluble expression of GSAI, depending on conditions, which increased the yield of soluble GSAI by about 5.1-fold compared to the untagged control, and approximately 55% for THAI. Following thrombin-mediated tag removal, thermophilic GSAI retained its original enzymatic activity, and CD measurements confirmed that its secondary structure remained unchanged. Although THAI remained intrinsically unstable after cleavage, the fusion system enabled recovery of detectable activity for the first time. These results identify the halophilic PPIase from C. salexigens as a robust fusion partner that promotes solubilization and proper folding of difficult-to-express proteins in Escherichia coli , providing a platform for improved recombinant protein production and potentially advancing D -tagatose manufacturing. DOI： 10.1016/j.jbiotec.2026.02.013 Scopus PubMed
• 3-1-3 Isolation and characterization of peanut nodule-associated bacteria in Myanmar（3-1 土壌生物の生態と機能 2024年度福岡大会） . 日本土壌肥料学会講演要旨集70 ( 0 ) 25 -2024 · 記述言語： 日本語 出版者・発行元： 一般社団法人 日本土壌肥料学会 DOI： 10.20710/dohikouen.70.0_25_3 CiNii Research
• 3-1-4 Isolation and Characterization of Mung bean Rhizobia in Myanmar（3-1 土壌生物の生態と機能 2023年度愛媛大会） . 日本土壌肥料学会講演要旨集69 ( 0 ) 28 - 282023 · 記述言語： 日本語 出版者・発行元： 一般社団法人 日本土壌肥料学会 DOI： 10.20710/dohikouen.69.0_28_1 CiNii Research
• Ura T., Kameda T., Laksmi F.A., Ishibashi M., Arakawa T., Shiraki K., Hirano A. . Affinity of phenolic compounds for transition metal ions immobilized on cation-exchange columns . Jour2022 · 記述言語： 日本語 出版者・発行元： Journal of Chromatography A Immobilized metal ion affinity chromatography (IMAC) is useful in purification of histidine-tagged or histidine-rich proteins and peptides from a variety of hosts. However, phenolic compounds including polyphenols interfere with IMAC due to their high affinities for the transition metals immobilized on the column resins, which hampers the purification of proteins from plant-based host systems. In contrast to extensive knowledge of the mechanism of the interactions between phenolic compounds and transition metal ions in solution, an understanding of the interactions on the columns, where transition metal ions are immobilized on the resins, remains elusive. This study systematically investigated the affinity of phenolic compounds for transition metal ions by varying the number and position of phenolic hydroxyl groups (OH groups) and using different transition metals—Fe(II), Cu(II) and Ni(II)—on various IMACs, in which the columns were fabricated by equilibrating the cation-exchange column with transition metal solutions. It was found that the more OH groups the aromatic compounds have, the higher the affinity for transition metal ions; in particular, methyl gallate and pyrogallol were permanently bound to the IMAC column, which reflected coordinate bond formation with the transition metal ions. Importantly, the phenolic compounds showed no obvious affinity for the Ni(II)-IMAC column, in contrast to the Fe(II)- and Cu(II)-IMAC columns, whereas imidazole and histidine-tagged proteins showed evident binding to the Ni(II)-IMAC column. Ni(II)-IMAC should thus be especially effective in isolating histidine-tagged and histidine-rich species from phenolic compound-containing systems. These results indicate that the affinity between phenolic compounds and transition metal ions on the column is consistent with the results in solution. They also provide a comprehensive view for devising strategies to improve IMAC purification of target proteins and peptides from samples containing phenolic compounds. DOI： 10.1016/j.chroma.2022.463277 Scopus PubMed

• 好塩性酵素を産業に生かす
• 超安定化酵素の創製-その極立った構造可逆性のメカニズム
• halophilic enzyme
• 高度好塩菌蛋白質の高次構造形成と分子育種

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