Figure 1.

Epicyclic DNA loop constructions on the nucleosome core. Superposed structures of the IN42 and IN21 loops (with inserted DNA in orange and red, respectively). The helical axes of the loops and of the native nucleosome are shown as thick black lines. Histones are shown in grey and the arginines contacting the DNA minor groove are shown as green spheres (−1 → −7) and pink spheres (+1 → +7). Following the numbering of PDB entry 1KX5, arginines, from +1 to +7 are H4.R45, H3.R63, H3.R83, H2A.R42, H2A.R29, H2A.R77, H3.R49. See also Supplementary Figure S1.