The secondary structure generated by RNAalifold is shown in Figure 3. Arrows indicate ribonucleotides for which chemical probing experiments revealed accessibility to modification by kethoxal (red rectangles) or DMS (green circles).
Cysteine residues were added to predicted intra- and extracellular loops and the relative accessibilities to covalent modification by membrane impermeant biotin-maleimide determined.
Together these epigenetic modifications control chromatin accessibility to factors that regulate RNA polymerase II (Pol II) transcription (Additional file 1: Figure S1) [ 21, 22].
They include adjacent DNA elements and/or post-translational modifications of E2F protein, which may increase binding affinity, as well as chromatin modifications that would increase accessibility to the DNA and E2F interactions with other transcription factors, which allow the formation of more stable, cooperative multimeric complexes [8].
For various species, from yeast to plants and mammals, natural populations were found to display substantial variation in several chromatin hallmarks, including DNA methylation [ 1– 5], histone post-translational modifications [ 6– 9] and accessibility to DNA [ 10, 11].
The N-terminal tails of the histones protrude out from the histone octamer and are subjected to post-translational modifications that dictate the accessibility to the DNA by, e.g., transcription factors.
Accessibility to these sites is mediated by epigenetic modifications of histones and DNA.
Our gating model is validated by functional studies, including cysteine modification data indicating wider accessibility to the GluN1 M3 helices than to the GluN2A M3 helices from the lumen of the open channel, and reveals why the Lurcher mutation in GluN1 has a stronger ability in maintaining channel opening than the counterpart in GluN2A.
HDACs target nucleosomal histone proteins to create modifications that alter gene promoter accessibility to transcriptional regulators.
These modifications determine the genome's accessibility to transcription factors (Tan et al. 2011).
Such modifications modulate the compaction of chromatin and its general accessibility to transcriptional machinery.
