Bacterial Cell Biology and Physiology, Swammerdam Institute for Life Science, University of Amsterdam, 1098 XH Amsterdam, The Netherlands.
de Duve Institute, Université Catholique de Louvain, B-1200 Brussels, Belgium.
Int J Mol Sci. 2021 Feb 12;22(4):1853. doi: 10.3390/ijms22041853.
Gram-negative bacteria possess a three-layered envelope composed of an inner membrane, surrounded by a peptidoglycan (PG) layer, enclosed by an outer membrane. The envelope ensures protection against diverse hostile milieus and offers an effective barrier against antibiotics. The layers are connected to each other through many protein interactions. Bacteria evolved sophisticated machineries that maintain the integrity and the functionality of each layer. The β-barrel assembly machinery (BAM), for example, is responsible for the insertion of the outer membrane integral proteins including the lipopolysaccharide transport machinery protein LptD. Labelling bacterial cells with BAM-specific fluorescent antibodies revealed the spatial arrangement between the machinery and the PG layer. The antibody detection of each BAM subunit required the enzymatic digestion of the PG layer. Enhancing the spacing between the outer membrane and PG does not abolish this prerequisite. This suggests that BAM locally sets the distance between OM and the PG layer. Our results shed new light on the local organization of the envelope.
革兰氏阴性菌具有由内膜、肽聚糖（PG）层包围的三层包膜，由外膜封闭。包膜确保了对各种恶劣环境的保护，并为抗生素提供了有效的屏障。这些层通过许多蛋白质相互作用连接在一起。细菌进化出了复杂的机制来维持每个层的完整性和功能。例如，β-桶组装机制（BAM）负责插入外膜整合蛋白，包括脂多糖转运机制蛋白 LptD。用 BAM 特异性荧光抗体标记细菌细胞揭示了该机制与 PG 层之间的空间排列。每个 BAM 亚基的抗体检测都需要 PG 层的酶消化。增加外膜和 PG 之间的间距并不会消除这一前提条件。这表明 BAM 局部设定了 OM 和 PG 层之间的距离。我们的结果为包膜的局部组织提供了新的线索。
