title: Characterization of a mazEF toxin-antitoxin homologue from Staphylococcus equorum.
abstract: Toxin-antitoxin (TA) systems encoded in prokaryotic genomes fall into five types, typically composed of two distinct small molecules, an endotoxic protein and a cis-encoded antitoxin of ribonucleic or proteinaceous nature. In silico analysis revealed seven putative type I and three putative type II TA systems in the genome of the nonpathogenic species strain Staphylococcus equorum SE3. Among these, a MazEF system orthologue termed MazEF(seq) was further characterized. 5' rapid amplification of cDNA ends (RACE) revealed the expression and the transcriptional start site of mazE(seq), indicating an immediately upstream promoter. Heterologous expression of the putative toxin-encoding mazF(seq) gene imposed growth cessation but not cell death on Escherichia coli. In vivo and in vitro, MazF(seq) was shown to cleave at UACAU motifs, which are remarkably abundant in a number of putative metabolic and regulatory S. equorum gene transcripts. Specific interaction between MazF(seq) and the putative cognate antitoxin MazE(seq) was demonstrated by bacterial two-hybrid analyses. These data strongly suggest that MazEF(seq) represents the first characterized TA system in a nonpathogenic Staphylococcus species and indicate that MazEF modules in staphylococci may also control processes beyond pathogenicity.
authors.affiliation: Department of Microbial Genetics, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Faculty of Science, University of Tübingen, Tübingen, Germany.
authors.forename: Christopher F
authors.initials: CF
authors.lastname: Schuster
authors.forename: Jung-Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Marcel
authors.initials: M
authors.lastname: Prax
authors.forename: Alexander
authors.initials: A
authors.lastname: Herbig
authors.forename: Kay
authors.initials: K
authors.lastname: Nieselt
authors.forename: Ralf
authors.initials: R
authors.lastname: Rosenstein
authors.forename: Masayori
authors.initials: M
authors.lastname: Inouye
authors.forename: Ralph
authors.initials: R
authors.lastname: Bertram
mesh_terms: D000595:Amino Acid Sequence; D000992:Antitoxins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism*; D001483:Base Sequence; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013210:Staphylococcus / Q000145:classification* / Q000378:metabolism*
chemical_list: D000992:Antitoxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D012329:RNA, Bacterial; D012333:RNA, Messenger