Control of IS911 target selection: How OrfA may ensure IS dispersion

Laboratoire de Microbiologie et Génétique Moléculaire (UMR 5100 CNRS - U.Toulouse-3), 118 rte. de Narbonne, Bât. IBCG, 31062 Toulouse Cedex 09, France.
Molecular Microbiology (Impact Factor: 4.42). 04/2007; 63(6):1701-9. DOI: 10.1111/j.1365-2958.2007.05615.x
Source: PubMed


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.

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Available from: Catherine Guynet, Oct 22, 2014
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    • "Instead, it has been shown to modify the stoichiometry of complexes formed with the 1-149 truncated forms of OrfAB [26]. In addition, in IS911 OrfA is involved with both heteromultimerization with OrfAB [41], as well as with its own homomultimerization and with the ability to stimulate minicircle insertion in vitro into target DNA not associated with the IS911 ends [28]. It is likely that these heteromultimers may also exist in our preparations, which consist of a mixture of OrfA and OrfAB [31]. "
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    Mobile DNA 01/2012; 3(1):1. DOI:10.1186/1759-8753-3-1 · 2.11 Impact Factor
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    • "OrfA does not bind IS911 ends but can form heteromultimers with OrfAB (Haren et al., 2000). It is not required but stimulates integration of the circular IS911 transposition intermediate (Rousseau et al., 2007; Ton-Hoang et al., 1997). To allow us to focus directly on OrfAB activity alone we abolished OrfA expression by eliminating the requirement for frameshifting in OrfAB expression. "
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    • "Arrows represent strand cleavage and transfer reactions that take place within the synaptic complex (SCA) or paired end complex (PEC). IS911 insertion is drawn as a nontargeted pathway [16,31,32]. In the synaptic complex B (SCB), proteins are represented as grey ellipses without implying OrfAB stoichiometry or the presence or absence of OrfA in the complex. "
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    Mobile DNA 06/2010; 1(1):16. DOI:10.1186/1759-8753-1-16 · 2.11 Impact Factor
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