title: Genetic identification of two functional regions in the antitoxin of the parD killer system of plasmid R1.
abstract: We report the identification and genetic analysis of mutants in the antitoxin of the parD (kis, kid) killer system of plasmid R1. Missense mutants placed at codons 10, 11, 12 and 18 maintained the antitoxin activity of Kis, but not the ability of this protein to co-regulate the parD system together with the Kid toxin. Deletion of the last 33 amino acids of Kis inactivated the antitoxin activity of the protein and reduced substantially, but not completely, its regulatory activity. These results define two functional regions in Kis: an amino-terminal region which is specifically involved in regulation, and a carboxy-terminal region of the protein, which is important both for its regulatory and antitoxin activities.
authors.affiliation: Centro de Investigaciones Biológicas (CSIC), Department of Molecular Microbiology, Velázquez 144, 28006, Madrid, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Santos-Sierra
authors.forename: Consolación
authors.initials: C
authors.lastname: Pardo-Abarrio
authors.forename: Rafael
authors.initials: R
authors.lastname: Giraldo
authors.forename: Ramón
authors.initials: R
authors.lastname: Díaz-Orejas
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon; D010957:Plasmids / Q000235:genetics*; D011815:R Factors / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C068354:Kis protein, Bacteria; C489746:ParD protein, E coli; C489749:ParD protein, Plasmid R1; C078613:parD protein, Bacteria