Drouillard Sophie, Poulet Laurent, Marechal Eric, Amato Alberto, Buon Laurine, Loiodice Mélanie, Helbert William
CERMAV, CNRS and Grenoble Alpes Université, BP53, 38000, Grenoble, Cedex 9, France.
Laboratoire de Physiologie Cellulaire Végétale, Université Grenoble Alpes, CEA, CNRS, INRAE, IRIG-LPCV, 38054, Grenoble, Cedex 9, France.
Carbohydr Res. 2022 May;515:108544. doi: 10.1016/j.carres.2022.108544. Epub 2022 Mar 28.
Noctoc commune is a cyanobacterium living in various and extreme environments. Its ability to survive in desert, on ice or high altitude is explained by its exceptional metabolism and its capacity to resist to desiccation. N. commune cells are embedded in a gelatinous matrix made of polysaccharides which fixes water and participates in maintaining the cells in hydrated conditions. The structure of the polysaccharide of N. commune harvested in Saint Martin d'Uriage (France) and the oligosaccharides obtained after its enzymatic degradation were determined. The repeating unit of the main chain is a tetra-saccharide: [→4)-β-D-Glcp-(1 → 4)-β-D-Xylp-(1 → 4)-β-D-Glcp-(1 → 4)-α-D-Galp-(1→], branched at position 6 of a glucose residue by a β-linked pyruvated glucuronic acid residue. About 30% of the Xylp residues were branched with a Xylf residue. Comparison of this structure with the polysaccharides secreted by other Nostoc species and strains suggest a strong selection pressure on the structure in agreement with its important biological role.
普通念珠藻是一种生活在各种极端环境中的蓝细菌。它能够在沙漠、冰面或高海拔地区生存，这归因于其特殊的新陈代谢以及抵抗干燥的能力。普通念珠藻细胞嵌入由多糖构成的凝胶状基质中，该基质固定水分并有助于使细胞保持水合状态。对在法国圣马丁迪于里亚采集的普通念珠藻多糖结构及其酶解后得到的寡糖进行了测定。主链的重复单元是一种四糖：[→4)-β-D-葡萄糖-(1→4)-β-D-木糖-(1→4)-β-D-葡萄糖-(1→4)-α-D-半乳糖-(1→]，在一个葡萄糖残基的6位通过一个β-连接的丙酮酸化葡萄糖醛酸残基分支。约30%的木糖残基与一个木糖醛酸残基分支。将该结构与其他念珠藻物种和菌株分泌的多糖进行比较，表明该结构受到强烈的选择压力，这与其重要的生物学作用相符。
