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Updated: Jun 12, 2025

High-throughput Purification of Affinity-tagged Recombinant Proteins
Published on: August 26, 2012
Structural basis of RNA polymerase II transcription on the H3-H4 octasome
Cheng-Han Ho1, Kayo Nozawa1, Masahiro Nishimura1
1Laboratory of Chromatin Structure and Function, Institute for Quantitative Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
Abstract:
The H3-H4 octasome is a nucleosome-like particle in which two DNA gyres are wrapped around each H3-H4 tetramer disk, forming a clamshell-like configuration. In the present study, we performed in vitro RNAPII transcription assays with the H3-H4 octasome and found that RNAPII transcribed the H3-H4 octasome more efficiently than the nucleosome. RNAPII paused at only one position, superhelical location (SHL) -4 in the H3-H4 octasome, in contrast to pausing at the SHL(-5), SHL(-2), and SHL(-1) positions in the nucleosome. Cryo-electron microscopy analysis revealed that two H3-H4 tetramer disks are retained when the RNAPII paused at the SHL(-4) position of the H3-H4 octasome. However, when RNAPII reached the SHL(-0.5) position, five base pairs before the dyad position of the H3-H4 octasome, the proximal H3-H4 tetramer was disassembled but the distal H3-H4 tetramer still remained on the DNA. Therefore, RNAPII efficiently transcribes the H3-H4 octasome by stepwise H3-H4 tetramer disassembly.
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