title: Escherichia coli dinJ-yafQ genes act as a toxin-antitoxin module.
abstract: Bacterial toxin-antitoxin (TA) systems are operons that code for a stable toxic protein and a labile antitoxin. TA modules are widespread on the chromosomes of free-living Bacteria and Archaea, where they presumably act as stress response elements. The chromosome of Escherichia coli K-12 encodes four known TA pairs, as well as the dinJ-yafQ operon, which is hypothesized to be a TA module based on operon organization similar to known TA genes. Induction of YafQ inhibited cell growth, but its toxicity was counteracted by coexpression of dinJ cloned on a separate plasmid. YafQ(His)(6) and DinJ proteins coeluted in Ni(2+)-affinity and gel filtration chromatography, implying the formation of a specific and stable YafQ-DinJ protein complex with an estimated molecular mass of c. 37.3 kDa. Induction of YafQ reduced protein synthesis up to 40% as judged by incorporation of [(35)S]-methionine, but did not influence the rates of DNA and RNA synthesis. Structure modelling of E. coli YafQ revealed its structural relationship with bacterial toxins of known structure suggesting that it might act as a sequence-specific mRNA endoribonuclease.
authors.affiliation: Department of Biochemistry and Biophysics, Faculty of Natural Sciences of Vilnius University, Vilnius, Lithuania.
authors.forename: Rūta
authors.initials: R
authors.lastname: Motiejūnaite
authors.forename: Julija
authors.initials: J
authors.lastname: Armalyte
authors.forename: Arvydas
authors.initials: A
authors.lastname: Markuckas
authors.forename: Edita
authors.initials: E
authors.lastname: Suziedeliene
mesh_terms: D000595:Amino Acid Sequence; D000992:Antitoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009876:Operon; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D000992:Antitoxins; D001427:Bacterial Toxins; D029968:Escherichia coli Proteins; D012333:RNA, Messenger; C523350:YafQ protein, E coli; D004722:Endoribonucleases