在谷氨酸棒杆菌中 V snapping 之前，隔膜细胞包膜的顺序组装。
Sequential assembly of the septal cell envelope prior to V snapping in Corynebacterium glutamicum.
机构信息
Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA.
Department of Chemistry, Stanford University, Stanford, CA, USA.
出版信息
Nat Chem Biol. 2019 Mar;15(3):221-231. doi: 10.1038/s41589-018-0206-1. Epub 2019 Jan 21.
Members of the Corynebacterineae, including Corynebacterium and Mycobacterium, have an atypical cell envelope characterized by an additional mycomembrane outside of the peptidoglycan layer. How this multilayered cell envelope is assembled remains unclear. Here, we tracked the assembly dynamics of different envelope layers in Corynebacterium glutamicum and Mycobacterium smegmatis by using metabolic labeling and found that the septal cell envelope is assembled sequentially in both species. Additionally, we demonstrate that in C. glutamicum, the peripheral peptidoglycan layer at the septal junction remains contiguous throughout septation, forming a diffusion barrier for the fluid mycomembrane. This diffusion barrier is resolved through perforations in the peripheral peptidoglycan, thus leading to the confluency of the mycomembrane before daughter cell separation (V snapping). Furthermore, the same junctional peptidoglycan also serves as a mechanical link holding the daughter cells together and undergoes mechanical fracture during V snapping. Finally, we show that normal V snapping in C. glutamicum depends on complete assembly of the septal cell envelope.
棒杆菌属和分枝杆菌属等棒杆菌族成员具有独特的细胞包膜，其在肽聚糖层外还有一层额外的细胞膜。目前尚不清楚这种多层细胞包膜是如何组装的。在这里，我们通过代谢标记法跟踪了谷氨酸棒杆菌和耻垢分枝杆菌不同包膜层的组装动态，结果表明这两个物种的隔膜细胞包膜都是按顺序组装的。此外，我们证明在谷氨酸棒杆菌中，隔膜交界处的周质肽聚糖层在整个隔膜形成过程中保持连续，为流动性的细胞膜提供了扩散屏障。通过周质肽聚糖的穿孔可以克服这种扩散屏障，从而导致细胞膜在子细胞分离（V 形分裂）之前融合。此外，相同的连接肽聚糖还起到机械连接子细胞的作用，并在 V 形分裂过程中发生机械断裂。最后，我们表明谷氨酸棒杆菌中正常的 V 形分裂依赖于隔膜细胞包膜的完全组装。
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