An Oxygen-Sensitive Toxin-Antitoxin System
Journal Article - Open Access
Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, Barcelona Spain
Pagination or Media Count:
The Hha and TomB proteins from Escherichia coli form an oxygen-dependent toxinantitoxin TA system. Here we show that YmoB, the Yersinia orthologue of TomB, and its single cysteine variant C117SYmoB can replace TomB as antitoxins in E. coli. In contrast to other TA systems, C117SYmoB transiently interacts with Hha rather than forming a stable complexand enhances the spontaneous oxidation of the Hha conserved cysteine residue to a -SOxH containing species sulfenic, sulfinic or sulfonic acid, which destabilizes the toxin. The nuclear magnetic resonance structure of C117SYmoB 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.