Nucleosome accessibility governed by the dimer/tetramer interface.

ABSTRACT: Nucleosomes are multi-component macromolecular assemblies which present a formidable obstacle to enzymatic activities that require access to the DNA, e.g. DNA and RNA polymerases. The mechanism and pathway(s) by which nucleosomes disassemble to allow DNA access are not well understood. Here we present evidence from single molecule FRET experiments for a previously uncharacterized intermediate structural state before H2A-H2B dimer release, which is characterized by an increased distance between H2B and the nucleosomal dyad. This suggests that the first step in nucleosome disassembly is the opening of the (H3-H4)(2) tetramer/(H2A-H2B) dimer interface, followed by H2A-H2B dimer release from the DNA and, lastly, (H3-H4)(2) tetramer removal. We estimate that the open intermediate state is popul

SUBMITTER: Bohm V 

PROVIDER: S-EPMC3082900 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature