Figure 5.

Structural bias in the formation of the Int E449K synaptic complexes with attL and attR sites. (A) Recombination products from plasmids encoding attL^TA (pMS92), attR^TA (pMS93), attB^TA (pRT603) and attP^TA (pRT701). Products (co-integrates 1 and 2) are derived from reactions between (i) pMS92 (attL^TA) and pMS93 (attR^TA) (ii) pMS92 and pMS92 (iii) pMS93 and pMS93 and (iv) pRT603 (attB^TA) and pRT701 (attP^TA). Each attachment site is represented as an arrow. The halves without the arrow heads are the B or P arms, the halves with the arrowheads are the B′ or P′ arms. B-type arms are blue and P-type arms are red. The structures of the proposed synaptic complexes are indicated by the alternative alignments of P or P′ and B or B′ arms. The putative synaptic tetramer of integrase subunits is shown with each subunit coloured according to whether it is interacting with a B-type arm (blue) or a P-type (red). Int interactions at the synaptic interface are either complementary (Int bound to P-type arms interact with Int bound to B-type arms) or non-complementary (Int subunits that are both bound to P-type or B-type arms). The positions of relevant restriction sites are indicated (B, BamHI; X, XbaI) and the expected restriction fragment sizes of the parental plasmids and the co-integrate products are shown.