title: Discovery of functional toxin/antitoxin systems in bacteria by shotgun cloning.
abstract: Toxin-antitoxin (TA) modules, composed of a toxic protein and a counteracting antitoxin, play important roles in bacterial physiology. We examined the experimental insertion of 1.5 million genes from 388 microbial genomes into an Escherichia coli host using more than 8.5 million random clones. This revealed hundreds of genes (toxins) that could only be cloned when the neighboring gene (antitoxin) was present on the same clone. Clustering of these genes revealed TA families widespread in bacterial genomes, some of which deviate from the classical characteristics previously described for such modules. Introduction of these genes into E. coli validated that the toxin toxicity is mitigated by the antitoxin. Infection experiments with T7 phage showed that two of the new modules can provide resistance against phage. Moreover, our experiments revealed an "antidefense" protein in phage T7 that neutralizes phage resistance. Our results expose active fronts in the arms race between bacteria and phage.
authors.affiliation: Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Hila
authors.initials: H
authors.lastname: Sberro
authors.forename: Azita
authors.initials: A
authors.lastname: Leavitt
authors.forename: Ruth
authors.initials: R
authors.lastname: Kiro
authors.forename: Eugene
authors.initials: E
authors.lastname: Koh
authors.forename: Yoav
authors.initials: Y
authors.lastname: Peleg
authors.forename: Udi
authors.initials: U
authors.lastname: Qimron
authors.forename: Rotem
authors.initials: R
authors.lastname: Sorek
mesh_terms: D000992:Antitoxins / Q000235:genetics* / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism; D017123:Bacteriophage T7 / Q000472:pathogenicity; D003001:Cloning, Molecular / Q000379:methods*; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000821:virology; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D016680:Genome, Bacterial; D054884:Host-Pathogen Interactions; D005810:Multigene Family; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014774:Virulence
chemical_list: D000992:Antitoxins; D001427:Bacterial Toxins; D029968:Escherichia coli Proteins