title: An oxygen-sensitive toxin-antitoxin system.
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.
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Oriol
authors.initials: O
authors.lastname: Marimon
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: João M C
authors.initials: JM
authors.lastname: Teixeira
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Tiago N
authors.initials: TN
authors.lastname: Cordeiro
authors.affiliation: Department of Chemical Engineering and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Valerie W C
authors.initials: VW
authors.lastname: Soo
authors.affiliation: Department of Chemical Engineering and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Thammajun L
authors.initials: TL
authors.lastname: Wood
authors.affiliation: Swedish NMR Centre, Gothenburg University, PO Box 465, Gothenburg SE-40530, Sweden.
authors.forename: Maxim
authors.initials: M
authors.lastname: Mayzel
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Amata
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.|Institute for Research in Biomedicine (IRB-Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: García
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Ainara
authors.initials: A
authors.lastname: Morera
authors.affiliation: Institute for Research in Biomedicine (IRB-Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Gay
authors.affiliation: Institute for Research in Biomedicine (IRB-Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Marta
authors.initials: M
authors.lastname: Vilaseca
authors.affiliation: Swedish NMR Centre, Gothenburg University, PO Box 465, Gothenburg SE-40530, Sweden.
authors.forename: Vladislav Yu
authors.initials: VY
authors.lastname: Orekhov
authors.affiliation: Department of Chemical Engineering and Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: Thomas K
authors.identifier: 0000-0002-6258-529X
authors.initials: TK
authors.lastname: Wood
authors.affiliation: Biomolecular NMR Laboratory, Organic Chemistry Section, Inorganic and Organic Chemistry Department, University of Barcelona, Baldiri Reixac 10-12, Barcelona 08028, Spain.
authors.forename: Miquel
authors.identifier: 0000-0002-0586-8322
authors.initials: M
authors.lastname: Pons
mesh_terms: D000595:Amino Acid Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D048168:Escherichia coli K12; D029968:Escherichia coli Proteins / Q000502:physiology*; D010084:Oxidation-Reduction; D011487:Protein Conformation; D000075704:Toxin-Antitoxin Systems / Q000502:physiology*; D015007:Yersinia / Q000737:chemistry
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C079209:hha protein, E coli