Fig. 3: Crystal structure, structural features and interactions of the ILPR 4C intramolecular i-motif 8AYG.
A 4C structure coloured by nucleotide type (green: C, blue: T, yellow: A, grey: backbone, red: water molecules) and 2Fobs – Fcalc electron density map contoured at 1.5 σ level (grey). B Schematic showing the two 4C intramolecular i-motifs as arranged in the asymmetric unit and the interactions they form. Both fold into a 3′E-topology with the outer CC pair at the 3′–end (red). C Top view of one 4C i-motif and schematic showing the arrangement of the TAT and ACA-loops at the wide and narrow grooves, respectively. D Intramolecular and E Intermolecular interactions formed by the two independent intramolecular 4C i-motif strands B and A present in the asymmetric unit. Each structure and schematic is coloured based on the flank or loop position in the sequence: flank-1 (purple), loop-1 (orange), loop-2 (dark green), loop-3 (light blue), flank-2 (pink), grey (C-core). The nucleotides involved in the hydrogen-bonds shown in the boxes are coloured by atom type. All bond distances are in Å. F Structural comparison of the two i-motifs in the asymmetric unit by overlapping Strand-A (red) and Strand-B (blue). G Crystal of the 4C i-motif.
