title: Control of IS911 target selection: how OrfA may ensure IS dispersion.
abstract: IS911 transposition involves a closed circular insertion sequence intermediate (IS-circle) and two IS-encoded proteins: the transposase OrfAB and OrfA which regulates IS911 insertion. OrfAB alone promotes insertion preferentially next to DNA sequences resembling IS911 ends while the addition of OrfA strongly stimulates insertion principally into DNA targets devoid of the IS911 end sequences. OrfAB shares its N-terminal region with OrfA. This includes a helix-turn-helix (HTH) motif and the first three of four heptads of a leucine zipper (LZ). OrfAB binds specifically to IS911 ends via its HTH whereas OrfA does not. We show here: that OrfA binds DNA non-specifically and that this requires the HTH; that OrfA LZ is required for its multimerization; and that both motifs are essential for OrfA activity. We propose that these OrfA properties are required to assemble a nucleoprotein complex committed to random IS911 insertion. This control of IS911 insertion activity by OrfA in this way would assure its dispersion.
authors: Laboratoire de Microbiologie et Génétique Moléculaire (UMR 5100 CNRS - U.Toulouse-3), 118 rte. de Narbonne, Bât. IBCG, 31062 Toulouse Cedex 09, France. philippe.rousseau@ibcg.biotoul.fr
authors: Philippe
authors: P
authors: Rousseau
authors: Céline
authors: C
authors: Loot
authors: Catherine
authors: C
authors: Guynet
authors: Yoan
authors: Y
authors: Ah-Seng
authors: Bao
authors: B
authors: Ton-Hoang
authors: Mick
authors: M
authors: Chandler
mesh_terms: D020134:Catalytic Domain / Q000235:genetics / Q000502:physiology; D004251:DNA Transposable Elements / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D016366:Open Reading Frames / Q000235:genetics; D019895:Transposases / Q000235:genetics / Q000502:physiology*
chemical_list: D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; D019895:Transposases