Figure 4.

Schematic representations of three possible models of the Mos1 transposase paired-ends complex. Transposase dimers are bound via two helix–turn–helix motifs (HTH1 and HTH2) to (a) parallel or (b) antiparallel IR DNA molecules. Alternatively, parallel IR DNA molecules are bound in a tetrameric assembly (c) in which each of the four transposases contain only one helix–turn–helix motif (HTH) and two transposases bind to each palindromic IR. The transposase is represented by three circles: two DNA-binding motifs (pale blue and orange) and a catalytic domain (purple). The IR DNA is shown by a green rectangle. The twofold axes of symmetry that would arise in each assembly are marked by red lines or dots and filled arrows and the DNA diffraction at 3.3 Å is denoted by a line of black circles.