Cell Surface of Lactococcus lactis Is Covered by a Protective Polysaccharide Pellicle
Cell Surface of Lactococcus lactis Is Covered by a Protective Polysaccharide Pellicle
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DOI：
10.1074/jbc.m109.082958
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发表时间：
2010-04-02
影响因子：
4.8
通讯作者：
Kulakauskas, Saulius
中科院分区：
文献类型：
--
作者：
Chapot-Chartier, Marie-Pierre;Vinogradov, Evgeny;Kulakauskas, Saulius
在革兰氏阳性菌中，非包膜性质的表面多糖(PS)的功能作用仍然知之甚少。在这里，我们报告了一种新的细胞壁PS膜存在于乳酸乳球菌的表面。在半液体培养条件下筛选了自发的PS阴性突变体，并将所有突变定位在编码PS生物合成的单个染色体上。PS分子由六糖磷酸重复单元组成，与其他细菌PS不同。利用互补原子力和透射电子显微镜技术，我们发现PS层形成了包围细胞的外膜。值得注意的是，我们发现这种细胞壁层提供了一种保护屏障，防止宿主吞噬小鼠巨噬细胞。综上所述，我们的结果表明PS膜可能代表了革兰氏阳性细菌的一种新的细胞膜结构成分。
In Gram-positive bacteria, the functional role of surface polysaccharides (PS) that are not of capsular nature remains poorly understood. Here, we report the presence of a novel cell wall PS pellicle on the surface of Lactococcus lactis. Spontaneous PS-negative mutants were selected using semi-liquid growth conditions, and all mutations were mapped in a single chromosomal locus coding for PS biosynthesis. PS molecules were shown to be composed of hexasaccharide phosphate repeating units that are distinct from other bacterial PS. Using complementary atomic force and transmission electron microscopy techniques, we showed that the PS layer forms an outer pellicle surrounding the cell. Notably, we found that this cell wall layer confers a protective barrier against host phagocytosis by murine macrophages. Altogether, our results suggest that the PS pellicle could represent a new cell envelope structural component of Gram-positive bacteria.