Ramírez Carbó Carlos A, Irazoki Oihane, Venkatesan Srutha, Chen Lauren J S, Morales Haylie A, Garcia Avila Assariel J, Cheung Hoi-Ling, Cava Felipe, Nan Beiyan
Department of Biology, Texas A&M University, College Station, Texas, USA.
The Genetics and Genomics Interdisciplinary Program, Texas A&M University, College Station, TX 77843, USA.
bioRxiv. 2025 Jun 26:2025.06.26.661752. doi: 10.1101/2025.06.26.661752.
Many bacteria form spores to endure unfavorable conditions. While generate endospores through cell division, sporulation in non-Firmicutes remains less understood. The Gram-negative bacterium 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 lytic transglycosylases (LTGs), with both LtgA and LtgB supporting rapid sporulation and LtgB alone driving slow sporulation. 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.
许多细菌形成芽孢以耐受不利条件。虽然[具体细菌名称未给出]通过细胞分裂产生内生孢子，但非厚壁菌门细菌的孢子形成仍了解较少。革兰氏阴性菌[具体细菌名称未给出]通过两种不同机制进行孢子形成：化学诱导触发的快速孢子形成和饥饿驱动的缓慢孢子形成，这两种过程均独立于细胞分裂发生。相反，这些过程依赖于溶菌转糖基酶（LTG）对肽聚糖（PG）细胞壁的完全降解，LtgA和LtgB均支持快速孢子形成，而仅LtgB驱动缓慢孢子形成。值得注意的是，在快速孢子形成过程中，LtgB调控LtgA对PG的降解速度，确保过程可控，防止PG突然分解和形成无抗性的假孢子。除了LTG之间的调控外，PG降解还受其合成的影响；表现出胞壁肽产量增加的细胞通常会规避孢子形成。这些发现不仅揭示了细菌孢子形成的新机制，还阐明了控制PG动态的调控网络。
