Fig. 2: Structures of the ds_{-27_+143}-R relaxosome, the ss_{-27_+8}ds_{+9_+143}-R relaxosome, and the fully-assembled ss_{-27_+8}ds_{+9_+143}-R relaxosome.

a DNA used to solve the structure of ds_{-27_+143}-R. Nomenclature and numbering is as in Fig. 1c. nic is indicated by an arrow. The region of DNA for which a model could be derived from the density is shown in bold. Replicative (R-strand) and transfer (T-strand) strands are indicated. Orange box locates the TE-binding site on the T-strand between bp_-2 and bp₊₉. b Structure of ds_{-27_+143}-R. This structure was derived from the “locally-refined” map shown in Supplementary Fig. 4a. Left: Two orientations of the complex. Proteins and DNA are shown in surface and ribbon, respectively, colour-coded dark and light blue for the T- and the R-strand respectively; red and pink for IHFα and IHFβ, respectively; pale yellow, bright yellow and olive green for TraY1, TraY2, and TraY3, respectively; and green for the only TraI part visible in the density for this complex, VH_{2A+2B/2B-like}. 5’ and 3’ end base pairs are labelled. Right: Schematic diagram of the structure in the orientation shown at upper left. The two arms of the dsDNA hairpin are labelled. Same colour-coding as at left is used. c DNA used to solve the structures of ss_{-27_+8}ds_{+9_+143}-R complex (Fig. 1c). nic, the region of DNA for which a model could be derived from the density, and the location of the TE-binding site on the T-strand are shown as in panel a. d Structure of ss_{-27_+8}ds_{+9_+143}-R. This model is derived from the locally-refined map described in Supplementary Fig. 4b. Proteins and DNA are shown in surface and ribbon, respectively, colour-coded as in panel b, except for the additional TE domain in orange. Left: Near-atomic resolution structure of the complex. Right: Schematic representation of the structure. 3’ and 5’ DNA ends are indicated as well as the location of the nic site. e Structure of the fully-assembled ss_{-27_+8}ds_{+9_+143}-R relaxosome. This model is derived from both the locally-refined and global maps reported in Supplementary Fig. 4b–d and h–j. Proteins and DNA are shown in surface and ribbon, respectively, colour-coded as in panel d. TraI AH + CTD is in violet and TraM is in magenta. Left: model of the complex. Right: Schematic diagram.