Structural analysis of the sheath of a sheathed bacterium, Leptothrix cholodnii
Structural analysis of the sheath of a sheathed bacterium, Leptothrix cholodnii
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DOI：
10.1016/j.ijbiomac.2005.09.002
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发表时间：
2005-10-30
影响因子：
8.2
通讯作者：
Koizumi, J
中科院分区：
文献类型：
--
作者：
Takeda, M;Makita, H;Koizumi, J
乔氏纤发菌是一种需氧鞘形成细菌，常发现于贫营养和富含金属的水生环境中。通过选择性裂解细胞来分离该细菌的鞘。鞘中的主要氨基酸为甘氨酸和半胱氨酸。鞘很容易溶解在联氨中，并从溶液中回收被半胱氨酸取代的多糖。通过气液色谱分析，在肼解产物中检测到半乳糖胺、葡萄糖胺和半乳糖醛酸。肼解产物的FAB-MS分析表明糖序列为HexN-GalA-HexN-HexN。甲基化连接分析显示存在4-连接的GalA、3-连接的HexN和4-连接的HexN。鞘的巯基用于用荧光试剂4-（氨基磺酰基）-7-氟-2，1，3-苯并恶二唑（ABD-F）标记。将标记的鞘（ABD鞘）部分水解，并通过HPLC纯化三个荧光片段。其中之一被鉴定为ABD-半胱氨酸。第二个是ABD-半胱氨酸四聚体。另一个片段通过核磁共振（NMR）分析表明是被ABD-半胱氨酸取代的五糖。可以假设鞘的多糖和肽部分通过半胱氨酸残基连接。肼解产物的NMR分析显示鞘的多糖部分由含有2-氨基-2-脱氧半乳糖醛酸（GaINA）的五糖重复单元构成，如下所示。-> 4）-α-GalNA-（1 -> 4）-α-D-GalN（p）-（1 -> 4）-α-D-GalA（p）-（1 -> 4）-β-D-GlcN（p）-（1 -> 3）-β-D-GalN（p）-（1 ->. (c)2005 Elsevier B. V.保留所有权利。
Leptothrix cholodnii is an aerobic sheath-forming bacterium often found in oligotrophic and metal-rich aquatic environments. The sheath of this bacterium was isolated by selectively lysing the cells. Glycine and cysteine were the major amino acids of the sheath. The sheath was readily dissolved in hydrazine, and a polysaccharide substituted with cysteine was recovered from the solution. Galactosamine, glucosamine and galacturonic acid were detected in the hydrazinolysate by gas liquid chromatography analysis. FAB-MS analysis of the hydrazinolysate suggested a sugar sequence of HexN-GalA-HexN-HexN. Methylation linkage analysis revealed the presence of 4-linked GalA, 3-linked HexN and 4-linked HexN. The sulfhydryl groups of the sheath were used for labeling with the fluorogenic reagent, 4-(aminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (ABD-F). The labeled sheath (ABD-sheath) was partially hydrolyzed and three fluorescent fragments were purified by HPLC. One of them was identified as ABD-cysteine. The second one was found to be the ABD-cysteine tetramer. Another fragment was indicated to be a pentasaccharide substituted with ABD-cysteine by nuclear magnetic resonance (NMR) analysis. It can be assumed that the polysaccharide and peptide moieties of the sheath are connected by a cysteine residue. NMR analysis of the hydrazinolysate revealed that the polysaccharide moiety of the sheath was constructed from a pentasaccharide repeating unit containing 2-amino-2-deoxygalacturonic acid (GaINA), as shown below. -> 4)-alpha-GalNA-(1 -> 4)-alpha-D-GalN(p)-(1 -> 4)-alpha-D-GalA(p)-(1 -> 4)-beta-D-GlcN(p)-(1 -> 3)-beta-D-GalN(p)-(1 ->. (c) 2005 Elsevier B.V. All rights reserved.