基于程序性肽聚糖降解的细菌孢子形成形态变化新机制
A novel mechanism for morphological change during bacterial sporulation based on programmed peptidoglycan degradation
黄色黏球菌（Myxococcus xanthus）通过不依赖细胞分裂的两种途径形成孢子，均依赖裂解性转糖基酶 LtgA 和 LtgB 对肽聚糖（PG）细胞壁的完全降解。在化学诱导的快速产孢中，LtgB 程序化调控 LtgA 降解 PG 的速度，避免 PG 骤然崩解和产生无抗性的假孢子。此外，PG 降解还受其合成影响，muropeptide 产量升高的细胞往往绕过产孢过程。该研究揭示了细菌产孢的新机制及 PG 动态调控网络。
来源：eLife · doi.org
Many bacteria form spores to endure unfavorable conditions. While Firmicutes generate endospores through cell division, sporulation in non-Firmicutes remains less understood. The Gram-negative bacterium Myxococcus xanthus undergoes sporulation through two distinct mechanisms: rapid sporulation triggered by chemical induction and slow sporulation driven by starvation, both occurring independently of cell division. Instead, these processes depend on the complete degradation of the peptidoglycan (PG) cell wall by two lytic transglycosylases (LTGs), LtgA and LtgB. Remarkably, LtgB programs the pace of PG degradation by LtgA during rapid sporulation, ensuring a controlled process that prevents abrupt PG breakdown and the formation of non-resistant pseudospores. In addition to regulation between LTGs, PG degradation is also influenced by its synthesis; cells exhibiting increased muropeptide production often circumvent sporulation. These findings not only reveal novel mechanisms of bacterial sporulation but also shed light on the regulatory network governing PG dynamics.