Figure 4. H1 compacts trinucleosomes.

(a) NLE-Tri was imaged by atomic force microscopy (AFM) in absence of H1_FL (left), or with a 1:1 ratio of H1 per tri-nucleosome (right). (b) Binned height profiles of both NLE-Tri alone and in the presence of H1_FL. A minimum of 9 separate images were used to complete height traces (Fig. S4A) on a total of 1005 nucleosomes either with or without H1_FL and those heights are depicted in this graph. The mean height distribution of NLE-Tri alone is ~1.2 nm and increases to ~1.5 nm in the presence of H1_FL. Importantly, the propensity for aggregates increases significantly with H1_FL present. (c) Each of the observed arrangements was seen in an open conformation (longer distance between the nucleosomes - open), or in a condensed conformation with closely spaced nucleosomes. Aggregation of sample was also observed. A minimum of seven separate images for both NLE alone or with H1_FL were used to count the number of trinucleosomes in each group for a total of 481 NLE-tri alone and 524 NLE-Tri with H1_FL. The graph depicts the number of trinucleosomes found in each group in the absence or presence of H1_FL.