The transition structure of chromatin fibers at the nanoscale probed by cryogenic electron tomography

Abstract

We show that the extracted native chromatin presents a bifurcated hierarchical structure. The transitional 30 nm chromatin branching structure is the penultimate structure presenting 30 nm chromatin fiber unwinding into multiple nucleosomal arrays. Some nucleosomal arrays form the helix ribbon structure, while others randomly twist. Our work provides structural insights on the regulation of eukaryotic transcription.