在维持细胞包膜恒温中,丁糖素完整性和外膜不对称性之间的分子相互作用
Sinjini Nandy1, Arshya F Tehrani1, Augusto C Hunt-Serracin1
1Department of Biological Sciences, The University of Texas at Dallas, Richardson, Texas, USA.
Journal of bacteriology
|September 18, 2025
概括
在Acinetobacter baumannii中的LD-转酶LDTJ酶对细胞外完整性至关重要. 它的缺失会破坏糖甘的合成,并引发压力反应,但这些效应被Mla途径抵消.
科学领域:
- 微生物学 微生物学
- 细胞生物学 细胞生物学
- 细菌病原体的产生
背景情况:
- 细菌细胞外,特别是外膜 (OM) 和糖素 (PG) 层,对于结构完整性和生存至关重要.
- 协调OM和PG稳态的分子机制尚未完全理解,尽管LD-转酶 (LDTs) 在PG交联中发挥着重要作用.
- 宝曼尼菌 (Acinetobacter baumannii) 是一种具有较高抗生素耐药性的重大机会性病原体,使其细胞外成为了解生存机制的关键目标.
研究的目的:
- 描述LD-转酶LdtJ在Acinetobacter baumannii中的功能.
- 研究LdtJ删除对细胞包膜恒温和细胞过程的生理后果.
- 探索LdtJ活动,糖甘合成和外膜脂质运输之间的相互作用.
主要方法:
- 基因操纵,包括在Acinetobacter baumannii中创造单 (∆ldtJ) 和双 (∆ldtJ ∆mla) 突变.
- 对细胞形态和生长表型的分析.
- 使用RNA测序来评估转录变化的基因表达概况.
- 测量严格的响应指标,如ppGpp水平和DksA表达.
主要成果:
- 删除LdtJ导致细胞形态的显著缺陷,降低糖素前体基因 (dadA, alr) 的调节,并激活严格反应 (升高ppGpp,DksA上调).
- 这些与LdtJ删除相关的缺陷在∆ldtJ ∆mla双突变中被完全抑制,这表明Mla途径参与OM脂质运输的补偿作用.
- RNA测序数据表明,在∆ldtJ突变体中观察到的转录变化在双突变体中被逆转,揭示了PG重塑和OM脂质不对称之间的功能联系.
结论:
- 在Acinetobacter baumannii中,LdtJ在维持细胞外完整性方面发挥着至关重要的作用,超出了它在糖交联中的已知功能.
- LdtJ影响更广泛的调节和代谢网络,包括严格反应和甘前体生物合成.
- 由LdtJ重塑二甲糖和通过Mla通路维持外膜脂质稳态之间存在一种以前未被识别的功能相互作用.
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