一种氧敏感的毒素-抗毒素系统。
An oxygen-sensitive toxin-antitoxin system.
机构信息
Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
Department of Chemical Engineering and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
出版信息
Nat Commun. 2016 Dec 8;7:13634. doi: 10.1038/ncomms13634.
The Hha and TomB proteins from Escherichia coli form an oxygen-dependent toxin-antitoxin (TA) system. Here we show that YmoB, the Yersinia orthologue of TomB, and its single cysteine variant [C117S]YmoB can replace TomB as antitoxins in E. coli. In contrast to other TA systems, [C117S]YmoB transiently interacts with Hha (rather than forming a stable complex) and enhances the spontaneous oxidation of the Hha conserved cysteine residue to a -SOH-containing species (sulfenic, sulfinic or sulfonic acid), which destabilizes the toxin. The nuclear magnetic resonance structure of [C117S]YmoB and the homology model of TomB show that the two proteins form a four-helix bundle with a conserved buried cysteine connected to the exterior by a channel with a diameter comparable to that of an oxygen molecule. The Hha interaction site is located on the opposite side of the helix bundle.
大肠杆菌的 Hha 和 TomB 蛋白形成一种依赖于氧气的毒素-抗毒素（TA）系统。在这里，我们发现 YmoB，即 TomB 的耶尔森氏菌同源物，及其单个半胱氨酸变异体 [C117S]YmoB 可以取代大肠杆菌中的 TomB 作为抗毒素。与其他 TA 系统不同，[C117S]YmoB 与 Hha 短暂相互作用（而不是形成稳定的复合物），并增强 Hha 保守半胱氨酸残基的自发氧化为含有 -SOH 的物种（亚磺酸、亚硫酸或磺酸），从而使毒素失稳。[C117S]YmoB 的核磁共振结构和 TomB 的同源模型表明，这两种蛋白质形成一个四螺旋束，其中一个保守的埋藏半胱氨酸通过一个直径与氧分子相当的通道与外部相连。Hha 的相互作用位点位于螺旋束的另一侧。
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