第三类分泌系统转位IpaC,SipC和BipC是部分折叠的α螺旋状蛋白质,缺乏三级结构
Jacob M Kroh1, Amritangshu Chakravarty1, Supratim Dey1
1Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas United States of America.
PloS one
|September 12, 2025
概括
细菌III型分泌系统 (T3SS) 的转位体对于毒性至关重要. 新的研究表明,这些必不可少的蛋白质主要具有二次的α-螺旋结构,缺乏复杂的三级折叠.
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:
- 第三类分泌系统 (T3SS) 对于细菌的毒性至关重要,它可以将效应蛋白注入宿主细胞.
- 转位子是T3SS注射体内形成毛孔的复合体,它促进了效应蛋白转位.
- 转位子是由主要和次要转位子组合在一起的,这两种转位子都对细菌感染至关重要.
研究的目的:
- 为了确定T3SS小转移的三维结构.
- 从关键细菌病原体中研究IpaC,SipC和BipC的结构特征.
主要方法:
- 蛋白质表达和IpaC,SipC和BipC的净化.
- 循环二重化 (CD) 光谱学.循环二重化 (CD) 光谱学.
- 热变质试验. 热变质试验. 热变质试验.
- 2D核磁共振 (2D NMR) 光谱学.
主要成果:
- IpaC,SipC和BipC成功地表达和净化.
- CD光谱,热变性和2DNMR证实了这些蛋白质是α-螺旋的.
- 转位物主要表现出二次结构,缺乏稳定的三级结构.
- BipC显示了一种混合的alpha-helical和随机的线圈形状.
结论:
- 包括IpaC,SipC和BipC在内的T3SS转位体主要由次要的α-螺旋结构组成.
- 这些必不可少的毒性蛋白似乎会组装成跨孔复合体,而不会形成稳定的三级结构.
- 这些发现挑战了关于T3SS转移结构复杂性的先前假设.
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