Figure 5.

The macro-linker extends protection of DNA flanking the nucleosome from exonuclease III digestion. End-positioned (0-N-33) nucleosomes containing major-type H2A, mH2A₁₂₂ or mH2A₁₆₁ were digested with increasing amounts of exonuclease III. DNA fragments contained the 5′-FAM label on the zero-end of the nucleosome. Increased digestion was apparent for mH2A₁₆₁ at ∼154 bp and ∼165 bp, corresponding to ∼81 bp and ∼92 bp from the nucleosome dyad (filled triangles). DNA appeared more protected at 132–135 bp, corresponding to ∼59–62 bp from the dyad (bracket), likely due to increased exonuclease III pausing at the nucleosome edge. M = marker, UP = unprocessed.