内部离子对通过TonB-依赖的 siderophore受体控制运输
Salete M Newton1, Phillip E Klebba1
1Department of Biochemistry & Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA.
International journal of molecular sciences
|February 27, 2026
概括
在TonB依赖的受体中保存的离子对网络对于将铁性 siderophores 运输到阴性细菌中至关重要. 破坏2位点的特定静电相互作用会显著损害营养吸收和细菌防御机制.
科学领域:
- 微生物学 微生物学
- 结构生物学 结构生物学
- 生物化学 生物化学
背景情况:
- 像FepA和FhuA这样的TonB依赖受体 (TBDRs) 促进铁性 siderophores等必需营养物的运输,通过Gram负细菌外膜.
- 吸收机制涉及位于C端β-桶 (CTβB) 通道内的N端光域 (NTLD) 内的构造变化.
研究的目的:
- 调查在NTLD-CTβB接口上保存的静电相互作用在TBDR函数中的作用.
- 确定特定离子对在介导铁性 siderophore 运输中的机械重要性.
主要方法:
- 在FepA和FhuA中设计了系统的氨酸替代物,以破坏四个已确定地点的保存离子对.
- 通过 siderophore 营养测试,素敏感性测试和光光谱测量吸收和结合亲和度来评估突变功能.
主要成果:
- 破坏2位点的静电键显著减少或取消铁基 siderophore 吸收和素易感性.
- 位点-2突变没有影响FepA与铁素肠杆菌素的结合亲和力,也没有影响FhuA与铁的结合亲和力.
- 消除其他部位 (1, 3, 4) 的相互作用并没有阻碍铁性肠杆菌素的吸收.
- 位点-2突变增加了对蛋白质分解的敏感性,表明NTLD不稳定.
结论:
- 2位点的进化保守的离子对对于铁性 siderophore 通过 CTβB 传输到周等离子体所需的构造变化至关重要.
- 这些静电相互作用在CTβB通道内稳定NTLD,在TBDR介导的营养吸收中发挥关键作用.
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