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Nat Commun. 2016 Dec 8;7:13634. doi: 10.1038/ncomms13634.

An oxygen-sensitive toxin-antitoxin system.

Author information

1
Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
2
Department of Chemical Engineering and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
3
Swedish NMR Centre, Gothenburg University, PO Box 465, Gothenburg SE-40530, Sweden.
4
Institute for Research in Biomedicine (IRB-Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain.

Abstract

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 -SOxH-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.

PMID:
27929062
PMCID:
PMC5155140
DOI:
10.1038/ncomms13634
[Indexed for MEDLINE]
Free PMC Article

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