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
bioRxiv : the preprint server for biology
|July 16, 2025
概括
细菌LdtJ酶对Acinetobacter baumannii的细胞外完整性至关重要,它影响糖体结构和细胞代谢. 破坏Mla通路可挽救由LdtJ损失引起的缺陷,揭示了脂质运输和细胞壁平衡之间的联系.
科学领域:
- 微生物学 微生物学
- 细菌细胞外结构和功能
- 格拉姆阴性细菌的发病因子
背景情况:
- 细菌细胞外,特别是在阴性细菌中,需要协调的外膜和糖层来保持结构完整性和生存.
- 连接外膜和类甘油平衡的分子机制尚不清楚.
- LD-转酶 (LDT) 是参与使用D-氨基酸进行类甘油交联的酶,但它们的完整生理作用仍未确定.
研究的目的:
- 为了描述LD-转酶LdtJ在Acinetobacter baumannii中的活性.
- 研究LdtJ删除对细胞形态,基因表达和应激反应的影响.
- 探索 LdtJ 功能,二甲基干稳定和外膜脂质运输之间的关系.
主要方法:
- 在Acinetobacter baumannii中的LdtJ酶的遗传删除.
- 对细胞形态,糖原体基因表达 (例如,dadA,alr) 和严格反应激活 (ppGpp,dksA) 的分析.
- 构建和分析 ΔldtJ Δmla 双变异体,并进行 RNA 测序,以评估转录变化.
主要成果:
- LdtJ 缺失导致细胞形态的显著缺陷,降低糖素前体基因的调节,并激活严格反应.
- 这些缺陷在 ΔldtJ Δmla 双重突变中被完全抑制,这表明 Mla 途径 (外膜脂质运输) 的补偿作用.
- RNA测序证实了 ΔldtJ 突变体中的转录性改变在双重突变体中被逆转,突出了丁糖和外膜脂质不对称之间的相互作用.
结论:
- 通过糖素的修饰和影响更广泛的代谢和调节网络,LdtJ有助于细菌包膜的完整性.
- 通过LdtJ重塑糖和由Mla通路调节的外膜脂质稳态之间存在以前未被识别的联系.
- 针对这些相互连接的途径可能会提供针对抗生素耐药性细菌的新策略,如Acinetobacter baumannii.
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