title: Structural and functional comparison between the stability systems ParD of plasmid R1 and Ccd of plasmid F.
abstract: The stability determined by the systems ParD of plasmid R1 and Ccd of plasmid F is due to the concerted action of two proteins, a cytotoxin and an antagonist of this function. In this paper we report that CcdA and Kis proteins, the antagonists of the Ccd and ParD systems respectively, share significant sequence homologies at both ends. In Kis, these regions seem to correspond to two different domains. Despite the structural similarities, Kis and CcdA are not interchangeable. In addition we have shown that the cytotoxins of these systems, the Kid and CcdB proteins, do not share structural homologies. In contrast to CcdB, the Kid protein of the ParD system induces RecA-dependent cleavage of the cI repressor of bacteriophage lambda very inefficiently or not at all. The functional implications of these results are discussed.
authors.affiliation: Centro de Investigaciones Biológicas (C.S.I.C.), Velázquez, Madrid, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Ruiz-Echevarría
authors.forename: G
authors.initials: G
authors.lastname: de Torrontegui
authors.forename: G
authors.initials: G
authors.lastname: Giménez-Gallego
authors.forename: R
authors.initials: R
authors.lastname: Díaz-Orejas
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001427:Bacterial Toxins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004265:DNA Helicases; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D005144:F Factor; D005816:Genetic Complementation Test; D005838:Genotype; D007700:Kinetics; D008969:Molecular Sequence Data; D009154:Mutation; D011506:Proteins; D011815:R Factors; D016415:Sequence Alignment; D015534:Trans-Activators
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; C068355:CcdA protein, Bacteria; C068356:CcdB protein, Plasmid F; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C068353:Kid protein, Bacteria; C068354:Kis protein, Bacteria; D011506:Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases