Action at a distance in Mu DNA transposition: an enhancer-like element is the site of action of supercoiling relief activity by integration host factor (IHF).

摘要: Abstract The first committed step in the vitro strand transfer reaction of a mini-Mu donor molecule is formation Type 1 complex which Mu ends are held together non-covalent protein-DNA complex. Efficient this at high levels supercoiling (sigma approximately -0.06) requires A and Escherichia coli HU proteins. At vivo supercoiling, efficient also E. integration host factor (IHF). We demonstrate that relief activity IHF mediated through an binding site early promoter region. This part larger enhancer-like element includes operator (01) 2 (02) with between. The stimulates initial rate 100-fold acts distance-independent fashion. Inversion orientation results total loss enhancer absence IHF. However, 10-fold stimulation induced by addition Furthermore, correct helical phasing between 01 02 required for maximal activity. indicate specific geometrical configuration element, sharp bend 02, optimal induction synapsis.