Fig. 1.

LX mediated ds ligation on reconstituted dinucleosomes and chromatosomes. (A) (Left) The efficiency of reconstitution of dinucleosomes and chromatosomes was analyzed by nucleoprotein agarose gel electrophoresis (lanes 2–4). Under empirically optimized conditions, nearly 100% efficiency of dinucleosome packing is achieved (compare lanes 1 and 2). (Right) The efficiency of ligation with naked DNA (lane 5), dinucleosome (lane 6), and chromatosome (lane 7) substrates. Immunodepletion of LX abolishes ligation (lanes 8–10). PI, Preimmune serum; α-LX, immunodepletion with α-XRCC4 antibodies. (B) Histone H1 inhibits LX ligation in the presence or absence of histone octamers. Reconstituted dinucleosomes (lanes 1–4) or corresponding equimolar concentrations of naked DNA (lanes 5–8) were preincubated with histone H1, and the resulting histone–DNA complexes were used as substrates for ligation by the LX complex. The presence of histone H1 causes a similar level of LX inhibition on both substrates. (All ligation reactions shown in all figures were repeated three to six times.)