Figure 7.

A sketch of the proposed cruciform drawn with the assumption that the structure is stabilized by the integrase. The L repeats (white boxes) are included in the hairpin arms since complementarity is observed to be important for binding (Results). The two spacers and the R repeats (grey boxes) are drawn outside the hairpin arms. The asymmetrical bases 23–25, 32, 39 are drawn as loops and bulges. Base pairing is visualized by short lines. Base pairing in the spacer region is assumed to be weakened upon extrusion of hairpins and therefore all base pairs are not shown.