title: Identification and characterization of type II toxin-antitoxin systems in the opportunistic pathogen Acinetobacter baumannii.
abstract: Acinetobacter baumannii is an opportunistic pathogen that causes nosocomial infections. Due to the ability to persist in the clinical environment and rapidly acquire antibiotic resistance, multidrug-resistant A. baumannii clones have spread in medical units in many countries in the last decade. The molecular basis of the emergence and spread of the successful multidrug-resistant A. baumannii clones is not understood. Bacterial toxin-antitoxin (TA) systems are abundant genetic loci harbored in low-copy-number plasmids and chromosomes and have been proposed to fulfill numerous functions, from plasmid stabilization to regulation of growth and death under stress conditions. In this study, we have performed a thorough bioinformatic search for type II TA systems in genomes of A. baumannii strains and estimated at least 15 possible TA gene pairs, 5 of which have been shown to be functional TA systems. Three of them were orthologs of bacterial and archaeal RelB/RelE, HicA/HicB, and HigB/HigA systems, and others were the unique SplT/SplA and CheT/CheA TA modules. The toxins of all five TA systems, when expressed in Escherichia coli, inhibited translation, causing RNA degradation. The HigB/HigA and SplT/SplA TA pairs of plasmid origin were highly prevalent in clinical multidrug-resistant A. baumannii isolates from Lithuanian hospitals belonging to the international clonal lineages known as European clone I (ECI) and ECII.
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Natural Sciences, Vilnius University, Vilnius, Lithuania.
authors.forename: Milda
authors.initials: M
authors.lastname: Jurenaite
authors.forename: Arvydas
authors.initials: A
authors.lastname: Markuckas
authors.forename: Edita
authors.initials: E
authors.lastname: Suziedeliene
mesh_terms: D040981:Acinetobacter baumannii / Q000235:genetics* / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics* / Q000378:metabolism*; D019295:Computational Biology; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D042822:Genomic Instability; D010957:Plasmids
chemical_list: D001427:Bacterial Toxins