title: The toxin-antitoxin system of the streptococcal plasmid pSM19035.
abstract: pSM19035 of the pathogenic bacterium Streptococcus pyogenes is a low-copy-number plasmid carrying erythromycin resistance, stably maintained in a broad range of gram-positive bacteria. We show here that the omega-epsilon-zeta operon of this plasmid constitutes a novel proteic plasmid addiction system in which the epsilon and zeta genes encode an antitoxin and toxin, respectively, while omega plays an autoregulatory function. Expression of toxin Zeta is bactericidal for the gram-positive Bacillus subtilis and bacteriostatic for the gram-negative Escherichia coli. The toxic effects of zeta gene expression in both bacterial species are counteracted by proper expression of epsilon. The epsilon-zeta toxin-antitoxin cassette stabilizes plasmids in E. coli less efficiently than in B. subtilis.
authors.affiliation: Department of Microbial Biochemistry, Institute of Biochemistry and Biophysics of the Polish Academy of Sciences, 02-106 Warsaw, Poland. ulazet@ibb.waw.pl
authors.forename: Urszula
authors.initials: U
authors.lastname: Zielenkiewicz
authors.forename: Piotr
authors.initials: P
authors.lastname: Ceglowski
mesh_terms: D000992:Antitoxins; D017931:DNA Primers; D024881:Drug Resistance, Bacterial / Q000235:genetics; D004917:Erythromycin / Q000494:pharmacology; D009876:Operon / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D015183:Restriction Mapping; D013297:Streptococcus pyogenes / Q000235:genetics*; D014118:Toxins, Biological
chemical_list: D000992:Antitoxins; D017931:DNA Primers; D014118:Toxins, Biological; D004917:Erythromycin