CHROMATIN ORGANIZATION IN THE SMALLEST FREE-LIVING EUKARYOTE OSTREOCOCCUS TAURI

Abstract

We have tested the polymer melt model in the smallest known, free-living eukaryote, Ostreococcus tauri, using cryoelectron tomography. Our results confirmed the prediction by the polymer melt model that the disordered nucleosomes in vivo could be induced into 30 nm fibers if the chromatin was diluted in a low-salt buffer. This conclusion, which helps us better understand the interactions between nucleosomes, also provides an explanation for why the 30 nm chromatin fiber was observed in previous studies. The highly flexible nature of nucleosome organization revealed by our experiments has important implications for uniting the structural basis of chromatin with the regulation mechanisms behind complex genome functions.