著者

小田 真隆

出版者

公益社団法人 日本薬学会

雑誌

YAKUGAKU ZASSHI (ISSN:00316903)

巻号頁・発行日

vol.129, no.10, pp.1233-1238, 2009-10-01 (Released:2009-10-01)

参考文献数

11

被引用文献数

1 1

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Bacillus cereus is one that causes of opportunistic human infections. Sphingomyelinase produced by B. cereus is assumed a virulence factor for the infection. Sphingomyelinase from Bacillus cereus (Bc-SMase) is Mg2+-containing metalloenzyme. Bc-SMase is a family of neutral SMase (nSMase) and mimics the actions of the endogenous mammalian nSMase in causing differentiation, development, and apoptosis. Bc-SMase may be a good model for the poorly characterized mammalian nSMase. Activation of Bc-SMase by divalent metal ions was in the order Co2+>Mn2+>Mg2+≫Ca2+>Sr2+. Crystal structure analysis of Bc-SMase bound to Co2+, Mg2+, or Ca2+ revealed that the water-bridged double divalent metal ions at the center of the cleft in both the Co2+- and Mg2+-bound forms is the catalytic architecture required for sphingomyelinase activity. In contrast, the architecture of Ca2+ binding at the site showed only one binding site. A further single metal-binding site existed at one side edge of the cleft. Based on the highly conserved nature of amino acid residues of the binding sites, the crystal structure of Bc-SMase with Mg2+ or Co2+ provided a common structural framework applicable to phosphohydrolases belonging to the DNase I-like folding superfamily. In addition, our analysis provided evidence that β-hairpin containing the aromatic amino acid residues and the metal ion of the side-edge participate in binding to sphinogmyelin and membranes containing sphingomyelin. This article summarized current knowledge of characteristics and mode of action of Bc-SMase.

著者

竹中 彰治 大島 勇人 寺尾 豊 小田 真隆

出版者

新潟大学

雑誌

基盤研究(C)

巻号頁・発行日

2014-04-01

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本研究の目的は、これまでの細菌を標的とした殺菌効果に頼ったバイオフィルム(BF)制御から、マトリックスを標的とした抗菌成分に頼らない新しい制御法への戦略の転換の必要性を提言するとともに、BFの剥離・分散効果に主眼を置いた新しいBF制御法を開発することであった。口腔内環境を再現した細菌培養システムと共焦点レーザー顕微鏡を用いた蛍光イメージング法により、殺菌効果に頼ったBF制御の弊害を明らかにした。そして、新しいコンセプトに基づくバイオフィルム制御剤の開発を進めた結果、細菌増殖に影響を与えることなく、BFの分散・剥離効果ならびに付着抑制効果を有する機能性糖脂質を見出した。

著者

中野 真代 小田 真隆 永浜 政博 山本 博文 今川 洋 櫻井 純 西沢 麦夫 樽井 敬史 渋谷 昌弘 大林 寿美代 玉城 翔太

出版者

天然有機化合物討論会実行委員会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

vol.54, pp.333-338, 2012

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Vizantine (3) is a synthetic derivative of treharose-6,6-dicorynomycolate (TDCM) which was characterized in 1993 as the cell surface glycolipid of Corynebacterium diphtheriae and shows a variety of significant biological activities for adjuvant development. In vitro, vizantine activates not only the macrophages of mice sera, but also induces the release of MIP-1β, IL-6, IL-8 etc. from human acute monocytic leukemia cell line cells (THP-1 cells). Because almost no TNF-α is induced in vivo, the lethal toxicity to animals was found to be ncredibly low. However, oral administration of vizantine to C57BL/6 mouse (p.o. 100 μg x 7 times) inhibits lung metastasis of B16-BL6 melanoma cells (which are classified in highly metastatic tumor cell). In recent years, structural components of the outer surface membrane of bacteria have attracted considerable attention as lead compounds for adjuvant development. However, a concern of the use of these compounds is that they can over-activate innate immune responses leading to the clinical symptoms of septic shock. Therefore, an important issue is a detailed knowledge of the immunostimulatory mechanism to harness beneficial effects without causing toxicity. Here, to advance the mechanistic studies of vizantine, we have synthesized magnetic beads-attached 4 that maintain immunological activities and can therefore act as a molecular probe. Using a pull-down assay of 4 and the extract of HEK-293T cells transfected with plasmid for TLR4 and MD2, vizantine was found to act as a ligand of the Toll-like receptor 4 (TLR4) and MD2 complex. Furthermore, the macrophage from TLR4 knockout (TLR4 -/-) mice showed decreased response to vizantine, but that from TLR2 knockout (TLR2 -/-) mice did not. Taken together the results suggest that vizantine suppresses the tumor lung metastasis through the activation of macrophages via TLR4/MD2 complex.