Slovak Academy of Sciences, Institute of Molecular Biology, Bratislava, Slovakia.
FEMS Microbiol Lett. 2011 Dec;325(1):92-8. doi: 10.1111/j.1574-6968.2011.02417.x. Epub 2011 Oct 3.
The cell wall is responsible for cell integrity and the maintenance of cell shape in bacteria. The Gram-positive bacterial cell wall consists of a thick peptidoglycan layer located on the outside of the cytoplasmic membrane. Bacterial cell membranes, like eukaryotic cell membranes, are known to contain domains of specific lipid and protein composition. Recently, using the membrane-binding fluorescent dye FM4-64, helix-like lipid structures extending along the long axis of the cell and consisting of negatively charged phospholipids were detected in the rod-shaped bacterium Bacillus subtilis. It was also shown that the cardiolipin-specific dye, nonyl acridine orange (NAO), is preferentially distributed at the cell poles and in the septal regions in both Escherichia coli and B. subtilis. These results suggest that phosphatidylglycerol is the principal component of the observed spiral domains in B. subtilis. Here, using the fluorescent dyes FM4-64 and NAO, we examined whether these lipid domains are linked to the presence of cell wall peptidoglycan. We show that in protoplasted cells, devoid of the peptidoglycan layer, helix-like lipid structures are not preserved. Specific lipid domains are also missing in cells depleted of MurG, an enzyme involved in peptidoglycan synthesis, indicating a link between lipid domain formation and peptidoglycan synthesis.
细胞壁负责细菌的细胞完整性和形状维持。革兰氏阳性细菌的细胞壁由位于细胞质膜外侧的厚肽聚糖层组成。与真核细胞膜一样，细菌细胞膜已知含有特定脂质和蛋白质组成的域。最近，使用膜结合荧光染料 FM4-64，在杆状细菌枯草芽孢杆菌中检测到沿细胞长轴延伸并由带负电荷的磷脂组成的螺旋状脂质结构。还表明，心脏脂特异染料壬基吖啶橙（NAO）在大肠杆菌和枯草芽孢杆菌的细胞极和隔膜区域优先分布。这些结果表明，磷脂酰甘油是枯草芽孢杆菌中观察到的螺旋结构域的主要成分。在这里，我们使用荧光染料 FM4-64 和 NAO，研究了这些脂质结构域是否与细胞壁肽聚糖的存在有关。我们表明，在原生质体细胞中，没有肽聚糖层，螺旋状脂质结构不能保存。在缺乏参与肽聚糖合成的酶 MurG 的细胞中，也缺少特定的脂质结构域，这表明脂质结构域的形成与肽聚糖的合成之间存在联系。
